[SiberianDVM]

I could use some help figuring out what is wrong with my car: stock 3.2L motor 1984 Carrera, does have cat delete and Steve Wong chip, running 93 octane supposedly ethanol free pump gas, just filled up that morning.

On the track at VIR this weekend, on 2nd run session, at about lap 5, on uphill straight at WOT, between 5000 and 5500 RPM in 4th gear, 110mph or so, car had momentary loss of power, like it was hitting the RPM limiter. Also did it in a couple of other places on the track at WOT, then it would run smooth.

Temp was good, just about 1st lower white mark. Oil pressure and levels were good. Pulled spark plugs and they looked good, nice and tan, no corrosion or pitting.

Put it back together, and final run session of the first day was about the same.

Instead of getting worse the second day, it got slightly better: still hesitated after it was hot, but not as bad. And just uphill at WOT this time. Bad gas? Semi-clogged fuel filter, fuel pump going bad? I really don't know where to start, as it runs fine under normal conditions. Any help appreciated.