Looking for a bit of advice or help with a slight issue I'm having. Car in question is a 2002 A3 1.8T sport 82k on the clock with the AUM engine fitted. I first noticed the problem a few weeks back when I was running an S2000 air filter and creations motorsport silicone TIP. So I put the mods back to standard and also fitted a brand new genuine MAF sensor. Took the car for a run and all seemed well until last night when I was giving an Accord type R a run for its money and at the top end of 3rd gear just as it hits 5500 RPM it just seems to hit a flat spot almost like a rev limiter but obviously a good way short of the actual rev limiter. The only mods on the car now are a R Tech stage 1 map and a deeper alloy side mount intercooler. No fault codes are stored and in 1st and 2nd gear it will rev past 6k it just seems to be 3rd gear thats the problem and I haven't tried 4th gear as its up into 3 figures by that point!
There's no boost leaks that I can see, all the vac pipes look in good order, pretty much all the breather pipes were replaced by the previous owner and it's also got a brand new genuine recirc valve fitted.
Seems a bit odd how it went back to working ok but now has faulted again.
Any help or advice greatly appreciated