Car shudders at certain speeds

[mercuryzephyrz7]

I finished installing my T-5 a few weeks ago and have had these horrendous wheels on it with more "oval" shaped wheel lug holes, so I thought that my car shaking at certain speeds was because of that.

Well, today I put on different wheels, and it still does it. Now, it's not as bad as it was...but it's still really bad.

It's fine first through second, but when I hit about 30 it will shake heavily ONLY if I let off the gas completely or just slightly hold it to speed. If I put my foot down and go faster, it feels fine.

I have also noticed it clunking when I let the clutch out, especially when the car is on a hill or something.

I'm assuming it's my U-joints and I'm going to do them this weekend, but would worn U-joints alone make the car shake and shudder as it was? The driveshaft was from my c4 and it fit in the T-5 just fine, I didn't have a problem with this before I originally took the motor out...but that was in July of 2008 so maybe it got worn out or dented possibly.

I'll have it out to inspect soon, but in the meantime do you guys think that my U-joints alone could make the car shake as it has been?

[NAVYCAT]

your drive shaft might be out of balance, remove the bolts and rotate the shaft 180* and try that