1MZFE Hesitation at WOT

[94CoupeV6]

The last couple days whenever I hit full throttle, the car sounds like it wants to go but it just doesn't have any power. Half throttle is quicker right now than full throttle even. It seems to run fine at any other throttle position other than WOT. Gas mileage has been very poor as well. I do have a good sized exhaust leak in my flex section of my y-pipe, so I'm thinking it could be giving that last O2 sensor in the cat a bad reading at full throttle. I may have a vacuum leak as well since the car idles at 950-1000 RPM, but this doesn't seem like it could be the problem. I was going to try and reset my ECU, since I had this problem once but it was fine after I reset it. This time I feel like it's different.

What do you think could be the culprit for this? If my cat O2 sensor is getting a bad signal, wouldn't that trigger a CEL? I do not have one, but there is something very wrong.

[samarai912]

you should get your flex pipe replaced. That would eliminate more possiblities. On my car I have never thrown a cel for an 02 sensor. but if one is has gone bad it should show up since it will be running in closed loop. it could also be your maf..have you cleaned it recently?