Ok I have a 95 rodeo 3.2L 4x4. Just bought it. Ran good when bought. The other day was goin down the road and it started running like crap. won't really go above 4000 rpm and then it sounds like the air intake is backfiring or something. Will not go above 4000 RPM. It is really hard to start when cold. Sometimes it backfires after being cranked. But after numerous tries (about 50) it finally starts. Still runs like crap though.
I have changed the following:

plugs
wires
coil packs
EGR valve
MAP sensor
CKP sensor (crank position sensor)
have taken off catalytic converter and it isnt clogged at all
changed oil and filter

the truck blows out white smoke when first started and then diminishes away, but it did that before this all started happening. I believe it is the valve seals leaking while parked. No CEL! (the CEL works because it illuminates when key is turned) I am so stumped here. Anyone have any ideas? Could the ECM be bad? Or the IAC or TPS?