Hello everyone, long time no post here, but here goes.

89rstrooper 2.6 rebuilt motor, new radiator, new fast idle solenoid, new throttle sensor( can't remember exactly if that is correct term for the part under the intake manifold that tapers to a point more or less)what else, basically too much money spent on the old girl in all areas.

Problems: the old surge problem, start it up idles a little high, drive it down the road until she is good and warm, come to a stop light & she starts surging from 600rpm or so to 2200rpm's more or less. I've cleaned & checked the egr no problems there. I also have a problem where sometimes, she'll start up and just rev scary rpms, very seldom though.

I was thinking shorted fuel injection wiring harness? Or bad fuel injectors? Maybe the ECM? Purely guessing at this point. Would a bad o2 sensor cause any of this? Pulling my hair out, she also pings & drinks ALOT of gas, there are these and a host of other probs but at this point these are the priorities.

I'm also in search of a 5spd trans/xfer case in one unit in good shape, preferably in Southern California or Arizona, while I'm dreaming anyway. To everyone that views this & has a suggestion, thank you in advance for your time! -Noel-

Air regulator is the thing under the intake manifold. Make sure the BLACK connector goes to it and that there's power. Check engine temperature sensor screwed into the underside of the intake and that the WHITE connector goes to it. They work in tandem. The temp sensor signals the ECM to inject more gas on a cold start. To check it:

"There are two connectors on a bracket just behind the battery. The larger of these two has the 2 wires from the temp sensor in it. They are BLACK and GREEN w)YELLOW stripe on my 88 truck. The way the connectors are mounted on my truck, these two wires are right on the top of the connector. Simply unplug the connector and put your ohmmeter across those two pins (DON'T BEND THE PINS!!!!)." - Troopershere

"degrees F / K ohms
14 / 7-12
50 / 3-5
68 / 2-3
122 / 0.7-1
176 / 0.2-0.4" - pucci

If you changed the throttle position sensor (little black box on the firewall side of the throttle body) you need to reset it:
"The prongs on the switch are labeled top to bottom, I, P and F. With the throttle closed, you should have no continuity between P-F and continuity between I-P. Slightly depressed gives no continuity between both of those sets of prongs and with it fully depressed (WOT), you should have continuity between P-F, but not I-P.
To adjust the switch, hook up the Ohm meter to I-P and place a 0.012 feeler gauge between the throttle stop and the throttle lever. Adjust the gauge until the point where the continuity is just established. Then use a 0.020 feeler gauge to make sure continuity is broken. At that point, it is adjusted." - Michael

Then of course there is the idle air controller on the top of the thermostat housing that's supposed to kick up the idle when the AC is on and the 02 sensor could cause similar symptoms. Don't you love these things? It's like a "Where's Waldo" hunt! I've had plenty of help from this board
(as you can see from the quotes) so welcome back to the best 'Zu info site.

Hey man thanks for the advice!! I'll give all that a try for sure. I haven't worked on the girl in about 6 months now since putting her aside for another truck, but am trying to get her road worthy to take down to Baja. I really appreciate the advice again! Take it easy & will let you know. -Noel-

I glanced over the post, but it sounds to me like the over heat air valve might be kicking on. (located on thermostate.) That will add 1000rpm. Also if it has A/C the air switch for that in the past has stuck open on my 90 trooper. Last check the air valve while its runing and see if the sensor is getting a steady 12V. You can also pull the engine control relay if you don't want to do while the engine is running. This will turn fuel pump with the ignition switch on. the air valve and fuel pump are on the same circut.