every so often when i shut the car off, or if ive been at a highway speed for a while, the engine will bog down under throttle (ie pop and bang instead of going up normally through the rpm band.). it still will accelerate, just with a lot of hesitation. it will usually clear up after a few shifts up and down. seems like its flooding or something. fyi i have upgraded to 92 octane with a octane booster to attempt clear out anything that maybe lurking in the heads fowling them up. anyone ever hear of this?

 

almost sounds like a tps going bad, could be an injector being stuck open and "flooding" it a little too.

 

Did you have the hesitation before the cold air intake?

Hesitation can also be due to a lean mixture or excessive EGR flow.

Are all your vacuum lines good, tight and on?

I've got a 150,000 mile '98 DOHC 5-sp which I've run at the drag strip, on a road course and I can't count the number of auto cross events.

But when when I bought it used with 96,000 miles, there were several vacuum hoses that had seen better days.

Knock on wood, the engine still runs fine.