HI,

I have had this problem intermittently for the last month, and it has really thrown me for a loop.

The Problem:

My engine won't rev above 5-6k after about 30 minutes of driving (city/highway). It will feel completely normal till it hits the wall, it feels like the ECU is limiting the engine.

However, during the same drive cycle, just earlier, I can redline the engine with no problems.

It doesn't happen every drive and the next time I start the car I am able to redline without issue (for the next 30 min....)

I am thinking either a fuel injection issue or overheating. However, lately it has only been 10C outside, so I doubt it is overheating (also my coolant temp is consistent to what it was before, approx. 190F).

Any ideas?? I have thought about resetting my ECU and checking my MAF, but looking for any other suggestions.

Notes: I have a tune from MM. And have checked for codes, there are none. I am running catless, and have the BHR coil pack (about 5k on them). I replaced my plugs approx 3k ago, and have been running 5W30 or 5W40 synthetic oil the last 2 oil changes. The last oil change was about 1k ago. AFRs seem to be consistent, during my drive.

Thanks in advance.