My daily driver is an '88 Cherokee with the 4.0 I-6 and auto tranny. This past weekend on Saturday I changed out the sending unit assembly on the gas tank because the old one was leaking where the wires went in. Starting on Tuesday or Wednesday it started running like total crap. I thought I had water in the gas so I added a couple bottles of heet to it. That helped a little bit. Now it just runs like crap when it warms up. It's fine when I first start it when it's cold. The engine will start idling really rough, and when I give it gas it will back fire through the TBI and spit and sputter has no power when I give it gas until I get the RPM's up. I changed the distributor cap and rotor back in March, I just put in a new fuel filter and plugs 2 days ago. There was some pretty crappy fuel that came out of the old fuel filter, which is only 6 months old too. I checked the new one tonight and it's still clean. If anyone has any ideas please post them up because I am out of them. Thanks in advance, Rick I finally got this thing running right. I checked everything under the hood that I could think of. Luckily I didn't have to spend any major $$$ on new parts. Anyways, I pulled the sending unit back out of the tank yesterday. It's running like a champ now.