Ibiza Mkv 1.2 BZG limited to 60mph and 3000rpm approx

Ibiza Mkv 1.2 BZG limited to 60mph and 3000rpm approx
No engine fault codes now. Runs fairly well on town roads but not on motorways slow to excelerate and won't exceed 60 mph and 3000rpm. History last 3 weeks poor running, Map sensor replaced, 1coil and lambda sensor all showed up on fault codes. Çar is running better but still the problem with motorway driving. No more fault codes so no clues there. Any ideas?

Can someone acknowledge my post so at least I know its on view

Thanks for the acknowledgement. Just to update all. So far and hopefully in order of replacement. MAF sensor replaced with correct Secondhand Bosch part sorted that error code. Spark Plug inspected replaced 3months ago, though a little sootted in appearance (running rich?) ignition coil definite faulty and replaced. Lamba sensor bank 1 showing rich replaced NGK part replace not sorted problem (heirsight not surprised as problem was more upstream) Air filter replaced dirty but not to excess. Fuel filter replaced.
Today I have interogated the ECU again with more comprehensive meter result as follows 2 faults

16556 - P0172 007 Bank1 Fuel measurement too rich sporadic
Measured Values (V) V1 2040/min
V2 00001000
V3 0.0
V4 0.920

17549 - P1149 Load Calculation check range performance sporadic
Measured Values (V) V1 40.2%
V2 -37.1%
V3 36.7%
V4 7<degree sign
V5 42.2%
V6 37.1%
V7 36.7%
V8 6<degree sign

My thoughts are the MAF sensor (being second hand, BUT not now showing a code) so ignoring the cost I'm veering more to an air leak, only problem is identifying which rubber tube is likely to be the culprit bearing in mind cooling and fuel hoses need to be ignored so actually how many should I be looking for, ideas welcomed and again thanks user jonial for his acknowledgement. I'll keep all updated

A good place to start to find air leaks is youtube from " Ratchets And Wrenches
Published on 18 Oct 2015" (unfortunately not able to state url's as I haven't made 15 posts yet) "How to Find and Fix Vacuum Leaks - Ultimate Guide" there are further video's from the author showing a methodical approach and the different component checks (causing air leaks and hence running problems) such as Brake booster, PCV valve, EGR valve. Hopefully I will find the cause sooner rather than later

Okay another update:- I mange to clear all fault code with the exception of one, that was triggered on engine load (motorway driving 60mph 3100rpm 5th gear) engine lost power and MIL lamp flashed intermittently, car hard shoulder ignition turned off, then back on MIL lamp distinguished and car drove "normally" again. ECU codes read and then cleared:- 16685 Cylinder 1 misfire.

The owner drove the car for a week commuting daily 7 miles each way. He soon reported the following:- Of a cold February morning the car drove poorly for the first mile or so finding it difficult to drive over a small hump back bridge. However driving home of a late afternoon the driver reported the car appeared to drive better. My thoughts is the cold start of a morning an issue?

I looked again at the car after this week and my thoughts and the engine ECU were investigated. I had sourced another coil pack for cylinder 1 though at this stage had not fitted it.

Starting the car it was not running correctly, a small but noticeable misfire at idle without the need for additional acceleration. ECU interrogated, 4 faults in following order:-
16685 Cylinder 1 misfire
16556 Fuel trim system too rich bank 1
17549 Load calculation cross check implausible
16556 Fuel trim system too rich bank 1

I cleared the codes and took the car on a 15 mile round trip interrogating the ECU and replacing coil cylinder 1 during the trip, the results were as follows.

Car drove for 4 miles, drive was not as well as previous week , ECU interrogated :-
17549 Load calculation cross check implausible
ECU Cleared
Car drove 3 miles , ECU interrogated :-
17549 Load calculation cross check implausible
ECU Cleared. Another coil fitted in cylinder 1
Car drove 4 miles ECU interrogated :-
17549 Load calculation cross check implausible
ECU Cleared.
Car drove 3 miles during which time in was drove hard (i.e. 3100rpm in 2nd or 3rd gear up a hill, the car's lost power and MIL lamp began to flash. Car stopped and restarted MIL lamp distinguished and drove a further mile. The car's ECU interrogated and not to surprisingly
16685 Cylinder 1 misfire REAPPEAR. !!!

Hi Guys I found the answer. In short a well and truly blocked CAT, a car that was saved from scrap yard heaven by the skin of its teeth. Luckily the ECU cut power to all the spark plugs, a pain in the arse to rectify which had an auto spark scratching his head for many hours. We came close to sending the ECU off to be tested at a cost of £70 plus p+p and would have taken over a week to receive back to be fitted back in the car. However I would like to thank them because they were happy to divulge to me that they had only 2 of these ecu's in the past (here's the big clue) both reporting misfires only the first on cylinder 2 and the second on cylinder 3, okay you say my was on cylinder 1 BUT both ECU's were returned to there owners with no faults found!!!
Power appeared to be reinstated to the spark plugs after the ECU was disconnected from the car for over 24 hrs, I had previously disconnected the battery for 20 mins+ but this had seemed to have no effect.

Possibly a quick way to see if the CAT is causing your lack of power is to remove the Pre-lambda sensor (though this maybe difficult to remove, my wasn't. NB bear in mind exhaust fumes will enter the engine bay and blacken its interior as well as fumes may enter the cars interior, Therefor this is only something I would do to diagnose a problem.

Hi you were the only person to reply to my cars issue so I thought you might be interested to see an up date