1995 Geo Tracker idle/temp issues?

Hey guys. I just bought a 1995 Geo Tracker 5spd RWD 8valve 4 banger. Test drove beautifully (probably 10-15 mins driving). On the way home after purchasing it, however, it began having some issues, the most prominent being a fluctuation in rpm’s when pressure is applied to the gas pedal. For instance, with the clutch pedal in, and the car between gears, when I push on the gas pedal, the rpm’s will spike (guessing above 2000 rpm) and then drop (probably under 1000 rpm). It will only do this when gas is applied and when the vehicle is warmed up (10+ mins of driving). It will also do this in first gear when letting off on the throttle. I have been told a various array of parts that could be the problem, such as the thermo gauge, the IAC, tps…the list goes on and on. I was wondering if there were any way to pintpoint this to a certain part. ALSO anyone know a good site for converting it to a 4x4? and where I could get some relatively inexpensive motor mounts (worn out, so causes lurching between gears when the clutch engages, or so I have been told). Your help would be greatly appreciated!
God Bless,
Not-so-mechanically-gifted college dude

Geo Tracket/Chevrolet tracker are the same vehicle, so a lot of those parts will interchange. Most yards will have an interchange list.

I once was talking to a guy about his…he’d lifted it, stuffed a 302 in it, with a 4X4 package, and put some rather large wheels/tires on it. He did go mudding with it, and has winches front and back, with a roll cage built into it. It was quite a sight, and there was even damage on the top of the rollcage, where it had been upside down.

Upgrading yours to 4X4 will require at minimum a heck of a lot of front end work. Transfer case, driveshafts front and rear, front hubs, front axle…for someone “Not-so-mechanically-gifted”…I’d recommend selling it, and getting one that already has 4X4 built in. There are a lot of them around…and a lot are better at being a 4X4 than the Geo Tracker.