When I got Dillon's '84 K5, he said the carb was bad, despite it being rebuilt twice. I picked it up and towed it to the lake I stayed at (Mason Lake) and checked it all out, fixed a wiring issue, put a battery in it and it fired up. At this point, I was wondering, what's wrong with the carb? It idled fine, didn't smoke; ran so good I decided to take it to a day Seattle trip rather than lug around the 25ft motorhome. It started loading up once on the trip, blew out some black smoke, but cleared out. Did that again once before I hooked it up to tow it home. I get home, and it seems to load up and sputter and backfire when it's cold, but clears out when it warms up and smooths out. So I get used to that. I drive it to Ione flawlessly. Does the same thing every time I start it up cold, but it would clear out and smooth out when it decided to, and I used it up there to do a few things. Then I put 3/4 ton axles under it and a 6" lift and 35's, and tow my trailer with it back to Spokane. Runs fine, but starts getting a bit warm on the temp gauge as I'm entering Spokane city limits. As soon as it gets hotter, it starts backfiring. When I say backfiring, I mean louder than gunshots. Kind of like a huge cannon being fired. I tried getting it all the way home with it loading up and backfiring along the way. I had people staring at me, slowing down, looking around, and I ran one guy off the road- when it backfired once so loud the car next to me swerved across opposing traffic lanes and went up onto the sidewalk and got out of his car and looked around cautiousely, only to see a red/white K5 and trailer lug up a hill sputtering. Because of it's irratic nature and such loud backfires that sounded like an electrical/spark issue, I theorized that the carb itself may not be the culprit. 305 Motor came out, 454 went in it... bypassing the '84 spark control computer and using a different distributor. The 305 and carb sat since then. Last week, I took the carb and put it on my '77 K5 with a 350. Fired right up. Ran smooth, didn't smoke or backfire. I drove it around a little (just the neighborhood). Moved it the other day, and it ran fine. Then, I go to start it and move it again, and it starts loading up. I rev it up to clear it out, and it starts acting like it's about to let off another cannonball again. So I parked it and shut it down. Appearently, the demons haven't left this carb yet.