ok, so I have done some searching but i cant tie all the info together yet. here's my problem, 89 renix ba10, at cold start it cranks over 4-6 times then revs to 2500 rpm before settling in around 600rpm or so. until the engine warms up there is a "dead spot" right off idle when you hit the gas.the rev up and the dead spot dont seem right and the idle sems too low... where do i begin diagnosing this? any and all help is much appreciated I'm new to jeeps and the forum.

 

This might help. Jeep Cherokee Engines - RENIX (non-HO) Engine Sensor Diagnostics

 

Dead spot? Like right as you step on the gas (throttle tip in)? Check fuel pressure. My 90 XJ did much the same for quite some time. I never could figure it out either. Until... The Jeep started backfiring and having otehr severe drivability issues...

MY problem was, after changing a headgasket (which it needed anyway), and buying a couple new sensors and swapping every other sensor out, swapping the ignition module and distributor and I can't remember what else, very low fuel pressure. And when I decided to swap the fuel pump (finally), the little piece of fuel hose on the pump IN THE TANK, was rotted. New hose and its been almsot a year and 10,000 miles...

Don't make the mistake of pressing the valve on the fuel rail and seeing hwo far it shoots... GET A GAUGE! Cheap one at Harbor Freight... About $15.

Not saying this is your issue, but look at that fuel pressure...

 

that is normal, if it stays at 2500 too long change the IAC.
that is too low, clean your TB around the throttle and eventually adjust idle with the screw.
low idle RPM, adjust TPS and check fuel press.
Check vacuum at MAP sensor as well.