1991 Prelude Si *--> I NEED HELP <--* !!!!!!!!!!!!!!!!!!!!?

Sounds like who ever you got the car from tried to do some light engine modification. The things you said i have seen happen with them cheap computer chips you can buy to get more horsepower. Pop your hood and look for two electical plugs going into the block..one comes from the intake manifold and one comes from the radiator. These are sensors. {on my honda they are green} pull them off and make sure there is nothing in the connections (it would look like a little cylinder from a circut board or something... than make sure they are firmly plugged back in...than go through and check all the wire connections making sure everything is plugged in tightly. This is definatly electrical and probably an easy fix.. aslo look near your intake tube and check those plugs also...good luck man , a prelude is a beautiful car