This is not a good thing....

[Frappe]

Sometimes, most often in 2nd gear, when I shift into the gear the car will spasm violently back and forth. Not like a "give me more gas before you let out the clutch" feeling, but it's like I'm mashing the gas and then releasing it over and over again very quickly. It's physically painful, and absolutely terrifying.

The previous owner of the car had installed a throttle body recently, so I will be checking that. It sounds like maybe a loose/bad Throttle Position Sensor, or Vacuum Seal problem...but I'm not really sure.

It will do it in the higher RPM range of 1st as well (4k+ usually) but not nearly as violently. In 2nd gear, it's mostly independent of what RPM I'm at, but tends to go away if I growly at the car, push on the gas pedal, and tap at the clutch a bit...but I think that's just luck. It tends to go away in 2nd gear also if I bring the RPMs to about 5k or so with the driveline engaged.

I'm going to take a look at the throttle body and all the vacuum lines I can see today, because this is making the car nearly undriveable and very uncomfortable.

If anyone else has ideas for things I might want to check, I'd really apprectiate it. Sorry about the long post.

oh yeah, if it makes any difference it's a 96 S14 with not quite 100k miles on the engine, and an awful awful second gear synchro.

-Frappe

Edit- would it be a worthwhile thing to change the transmission fluid while I'm at it? help with the shifting maybe?