I had my 01 4.6 V8 rebuilt 6 months ago and she purrs like a kitten but the whole truck shudders all the time and im not getting any trouble codes. Ive gone through everything I can think of. New plugs, injectors, coils, egr, harmonic balancer, knock sensor, nothing stops the shudder. I thought maybe the VCT solenoid but I guess they didnt have them until 04. The machinist that rebuilt it is rock solid too so I know whatever it is its not from the rebuild. Any ideas?

 

Have you pulled the inspection plate off of the bell housing and looked at the flywheel?

Also checked the bolts on the torque converter " assuming it's an AT ".

And nothing got between the tranny and the block when it was bolted back up?

That's the easy things to check that cost nothing but a little time and I've see it happen before and cause vibration.