Okay I am trying to piece this thoroughly so that way I dont spend money no needless stuff:

This is what happens:

At idle - when the car is stopped (Doesn't matter if its in neutral or in gear), if the needle is anywhere between 750 to 1000 RPM I feel a sorta of a vibration in the car - it like shakes rapidly but not very hard. There is no stuttering or backfiring or anything.

When I accelerate - if I accelerate lightly, I don't feel the vibration - but if I mash on it, when it gets to 3K RPM and above it starts vibrating again and stops at around 4K RPM.

Acceleration, I think, is a bit sluggish - but it may be due to my rear O2 sensor since I got a 0510 code and 0707 code (replacing O2 sensor soon), and my gas mileage got a bit crappy.

Now - what can cause these vibrations? I got the clutch swapped about 1200 miles ago - everything was tightened up as per spec, the motor mounts are fine so we shall exclude all of this. I have cleaned the TB but not the MAF - though it was not dirty. The MAF is plugged in properly and I double checked it a little while back. I get no misfire codes but I can't tell if it is or not since I don't hear any stuttering or bogging sounds. When I got my short shifter installed, on my way home the SES light was blinking at a random pattern - after a while it stopped but now its solid on (again, due to the rear O2 sensor)...

So - are my coils bad? My plugs bad? Something else I am missing?

 

Possible that the clutch was not aligned properly when installed. I also thought the '99's had one of those electronically controlled motor mounts? If it does, you may want to check that again?

 

Only SE is electronically controlled. The clutch was aligned as per spec... so I'd rule that out.

 

Could be a bad or loose motor mount. Check the rubber bushings for wear. Can also be caused by exhaust touching the body.

 

Any other suggestions?

 

I got the same vivration around 800 - 1k RPM after I had a new klutch kit put in a month ago. The flywheel was resurfaced too. So I think it is the clutch and/or the flywheel but it is too expensive to take everything apart again. The rpms also hang for a split of a second right where it vibrates.

 

Yeah exactly... damn...