88 Suburban 350 running badly, poor mileage. TBI rebuild time.

[L31MaxExpress]

So what happened between 7/15 and now? Last report I thought it was running rough? I’m wanting to do this IAC reset, but I feel I need some more electronic gadgets to do it.

If he made no changes perhaps it was actually running better and over a short period of time cleaned the carbon off the spark plugs, chambers, pistons and valves....The ECM may have also taken a little time to self adjust the fuel trims. It takes most ECM a couple of hundred miles to relearn when changes are made.

 

[geocrasher]

What changed? I put it back together 100% and drove it. It cleaned up pretty quickly. Part of the thick fuel smell was because I was running the truck with the TBI fully exposed, I think. I've yet to check the mileage but will report back when I have