I got a 99 burb with the 7.4 that I suspect was a shadetree job. **edit** and Tranny is 4L80e** She starts up, sounds great, but the idle continually slips from 1100 and down. Sometimes it settles @ 8 or 9 right after start up but continually slips either way. Sometimes she stalls and dies when you put it in reverse, if the engine doesn't die there's surging immediately afterwards. Dies at stopsigns, stoplights etc. There was also an issue with intermittent power under accelleration and some funny shifting. From a dead stop when you accelerate there's a pretty consistent *cough*hiccup* and then surge. There is/was also an issue shifting, wouldn't shift untill high rpm...wouldn't downshift under wot on the highway. I say is/was because it seems to have cleared up since I unhooked the battery fiddlin' with the EGR. Here is what I've done in the last three weeks in this order: --CES was on-- New Fuel Pump New Fuel Filter New TPS (started up and idled @ 1100, went for a cruise, engine cutting out, idle would later drop lower and lower as same problem returned) ---still had problem with intermittent power/engine cutting out under acceleration at this point--- New PCM from nelson Performance (has aftermarket GM cam*) -Started up, idled strong @ 1100 just like with the new TPS, but the problem returned also....went to autozone to pull the code...can't remember the exact code but I do have them written down somewhere..... Then while investigating EGR code and contemplating a new one discovered the wire loom had cooked on the exhaust return (it was just laying there!) and had melted through the plastic shield and one little gray wire was showing copper through its scorched insulation and making metal to metal contact with the return. 99% sure this wire was running to the EGR.... Seperated and insulated the wire, suspended the loom...unhooked the battery for a minute.....hooked it back up, started up -CES was off (as a result of discon battery?) -Idle is still awful -No more cutting out (yet) -Still hesitates/stalls/dies when moving to Rev or Drive -Shifting was way better on the test drive this time, under 10 or 15% throttle just scooted right along through all 4 gears, also downshifted when gettin' after it on the highway. So here's where I'm at, I pulled the EGR, but it didn't look like to me like it was bad, so I didn't install the new one I'd bought (but I've still got it). How can I be sure that the EGR is good? Am I hunting a possible vacuum leak now? All input is appreciated. *it's a mystery cam, I was able after some sleuthing to track down the fella that put the cam in, he gave me a part number but never answered another phone call....so at the bottom of my list is I still have no idea what cam is in it and this could be a possible issue... -Chris **disclaimer** I'm no expert and this is my first time to really go about sorting out an engine so If I ask a stupid question, please bear with me.