Weird idle

At a loss. Jeep runs good and strong, but idle bounces from almost zero and 650 rpm. 89 4.0 auto. I replaced the iac and tps, still idles wrong. Adjusted tps to .83 ratio. What next?

No body? Nothing? If I give it a strong rev, and let off it dies. It also doesn't want to start when it is hor?

The IAC is driven by 4 wires from the ECU. Check the wiring to make sure it is all good, beyond that, I would see if you can find another ECU to swap.

Got a volt ohmmeter? Where the TPS plugs into the harness, you'll see a black wire on the TPS side. Unplug the harness. At the harness side, probe the harness that the black wire goes to. I don't remember the color right now. With your VOM on the 200 scale, check the resistance between that harness pin and the engine. Should be darn near 0. If not, then your CTS, IAC, TPS, and possibly MAP sensors do not have proper ground and will send inaccurate info to the eCU.

Thanks for the ideas, hope it's a ground issue and not an ECM one.

Million to one.