As an Isuzu mechanic, I would not recommend an individual trying this. There is a large plate holding it in place, along with two snap rings behind it holding the bearing and seal in place.
The sister vehicle of the Isuzu Trooper is the Acura SLX
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.
I would start by checking the thermostat, it may not be opening.
Would have been built for R12, can be converted to R134a.
Bad gaskets- including a head gasket- would be a likely suspect.
Short in the wiring or one of the bulb receptacles.
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
If the check engine light is on...might be a dirty EGR valve.
Carb.? Float sticking and flooding
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.
Possible bad switches or partially disconnected wiring from the switches. Guess you'll need to pull the switches and check it out.