Bad gaskets- including a head gasket- would be a likely suspect.
The sister vehicle of the Isuzu Trooper is the Acura SLX
Short in the wiring or one of the bulb receptacles.
No they are too small a company. After working at a Gm, Suzuki, Isuzu dealership I would recomend a Suzuki
My guess would be wheel balance.
ECM
I would start by checking the thermostat, it may not be opening.
Would have been built for R12, can be converted to R134a.
blown head gasket
A person should be able to trouble shoot problems in a car. A vehicle would stall out after starting because of a failure in the fuel system, or it could be a bad O2 sensor.
check the timing.
5w-30 is the best to use on the trooper, i take it, it is the 3.0DT? Its a very fickle engine and doesnt like any other type
On my 1995 it is under the the dash where the clutch would be located. It is chrome colored and has plugin visible. I am certain the 1992 is identical.