4.0 difficult to start and won't idle
I searched yesterday and tried a few things last night, but it's still acting up. I have a 1997 Grand Cherokee with the 4.0 and 180,000 miles. I won't start most of the time unless I use the throttle and I have to keep on the throttle to keep it running. If I let off, it dies. I gave it a general tune up since it needed it anyway: plugs, wires, cap, rotor. I took the idle air control valve out last night and cleaned it up really well. There was lots of build up on it. It didn't help though, still stalls out. I don't want to buy parts to throw at it in hopes of fixing it unless I know for sure. Could it be the throttle position sensor on the throttle body? A friend mentioned crankshaft position sensor too.
Any help would be greatly appreciated. Currently my gf is driving my lifted Cherokee on 33s, which she loves, but need to get her Jeep fixed.