my 91 ctd has a terrible vibration, screws like to fall out into my lap once in awhile. it shakes the whole interior, but bring the engine up a couple hundred rpm's and it goes away. i've checked the motor and trans mounts,clutch fan etc.etc and i'm at a loss. anybody have any suggestions? thanks, pete

 

What's the idle speed?

 

Mine was doing the same thing and it was the exhaust toughing the frame somewhere. I adjusted the exhaust and no more vibe.

 

Mine will do that if the Idle is set too low...Everything would rattle in a strange harmony

 

Same with me.
My side pipe wired to the frame to keep it from just dangling there. Sometimes the wire gets a little lose and I gotta tighten it up a bit. Its not something I put off....it gets irritating REAL quick.

 

i turned the idle up quite a bit, and it still does it, especially when i put it in gear. exhaust isn't touching any where. thanks, pete

 

Sounds like a misfire. It's likely a bad injector. With it idling, crack one injector line at a time and see which one doesn't make it run worse.