Some driveability issues.

[VetteMed]

I've been driving the Z a lot these past 2 weeks (just about to roll over 191K miles), and I've noticed some consistent issues, I'm hoping someone may have some idea of where to start looking.

My daily commute has been about 2 hours each way for the last 2 weeks -- when I get about 45-50 minutes in to the trip, the idle begins to hunt up and down, by 200-300 rpm. It acts like a vacuum leak, but I'd expect a vacuum leak to be worse when cold, and improve when warm, as the metal parts expand.

Another issue I've noticed, and this also seems to not be an issue until the engine is fully warmed up, 40-50 minutes in to the trip, is that I get a bog / hesitation when rolling on to the throttle in a corner. Gentle sweeping turns in the road are not an issue, but an actual corner, taken at 20-30 mph, while in gear (usually 3rd or 4th), results in a complete loss of engine power, a bogging/hestitation sensation. As soon as I straighten out after the corner, power returns to normal and it runs fine.

Background info:
1991, 191K miles
Mostly stock, except for Jeal Headers, no cats, FIC injectors, secondary throttle plates removed, Haibeck PROM, 93-95 Injector housings.
Power seems to be excellent, fuel mileage as well (21-23 mpg).

Thanks,
Andrew