loud knock

I have a 91 gmc vandura. It was stolen and found. But when I got it back, it had a bad knocking(clunking almost). upon acceleration it seems to quiet up a bit. The weird thing is at idle it wants to die(squeaking sound). Could anyone with the knowledge help me out, I know this isn't very detailed.
Thanks

this sounds like a maiin or a rod bearing, if it is you will need to rebuild the bottom end of the engine, you may find it cheaper to replace the whole engine.maybe have a local mechanic have a listen to it to confirm.