rpms won't go over 1500!or 15 mph.

1993 Explorer-had a lot of work done in March to keep it running for my son. Yesterday, he was driving and car suddenly started shaking a bit and rpms wouldn't go over 1. Had to drive home at 10 mph. When parked, if you rev engine, rpms go up to right above 1 and drop back down. Needle freaks out back and forth. Engine shakes and makes weird noise. Not the transmission. Help!

could be anyone of nine million things.  the shaking issue would lead me to believe youre not running on all cylinders or your timing has been thrown way off, retarded.  I'd start with looking at the spark plug wires and spark plugs.  any error codes?

do  you smell rotten eggs in the exhaust?  i believe a clogged catalytic converter would cause the same problem.