Hey folks, I hope this is the right place for this post. I'm new and dumb.

The car's a 2.2L '98 Sunfire, manual tranny. I usually drive it nice as it's too slow to be fun anyway, but stretch it's legs occasionally. So I go out for a harder-than-usual drive, push it up to 5k between shifts, put the pedal down. All done with care, but the car is pushed hard, anyway.

After I do this, I go back to normal driving. For me, normal driving means it takes a mile to get up to highway speeds, lol. I accelerate slowly enough that the shift light tells me to change gears a bit before I hit 2k usually. So here I am, driving it nicely, and I get up to cruising at 50-55 (typical for me) in fifth gear. I don't have cruise. It's only when I start driving it nicely and usually when I hit this speed (think the tach is around 2k at these speeds) that the car starts hesitating, and bucking.

If I let off the gas completely, it stops bucking. If I nail the gas, it'll hesitate for a moment and then take off normally and smoothly.

Took me forever to establish a pattern, and I'm just now realizing that it's after the car gets beaten on that it does this. I have a friend that fixed this problem in his '86 Firebird with a fuel pump, but . . . well, way different engines, so you guys got any other ideas?

Also, can you get just a fuel pump or do you have to get the whole damn bulkhead assembly? Everywhere I've checked so far they quote me around $300 and it's of course for the whole assembly.

Thanks in advance for any help!

Oh, I should mention also that when it's bucking at highway speeds, pushing it to fourth gear usually smooths it out mostly.

One other thing is, just today it did this, but it got worse; I came to a stop and then when I tried to go, the damn thing just bogged down on me. Embarassing when you're at a busy four-way stop with people piled up all around! Lol. I had to very gently bring up the rpms to get it to go. Then I pulled over and floored it. The car hesitated, then jumped up to 2k, then bogged straight down to it's death. Started it up again, slowly brought the rpms up, and it happily hit 5k without hesitating - I just had to do it gradually. Now the problem has gone away, as I've been driving it nicely for a while.

I should also mention that I tried new plugs and wires, to no avail. Also just cleaned and re-greased the K&N air filter and have thrown fuel system cleaner in every few thousand miles.

Thanks!

Hmmm, have you changed the fuel filter before. You didn't mention how many miles you have on the car.

I haven't changed the fuel filter yet. I bought it at 150k and it now has 160k.

For what it's worth, the oil gets changed every 2k with a FRAM X2 filter and Mobil 1 synthetic oil, along with engine restore.

!!!!!!!!!!!!!!!

IMHO

Change the fuel filter.

Stick with M1 but change at 5k (or 10k like me).

Use M1 filter or Purolator filter.

changing you synthetic at 2k is way too soon and stop using @!#$ ass fram filters.