CarolinaChevyDad
Newbie
Its a 99 K3500 with the factory NV4500 trans (4x4 obviously) that I just bought a week ago. It drove great the first 600 miles and towed my car home on a trailer from a few states away where I bought it. Just this weekend, it started dropping to 350-500rpm when I would push in the clutch or put into neutral when slowing down to a stop sign. Sometimes it would stall and sometimes it would catch itself and come back to about 600rpm and stay running. Didn't pay attention to idle before just knew it seemed to be running fine. No check engine light and still has good power when in gear and accelerating. Doesn't sound like its missing at all like an injector or spark issue and plenty of power makes me think fuel pump/filter are good. Air filter needs replacing, but removing it didn't help. The only thing I did was put in a new alternator the day before because the old one was making a horrible sound. Was at 14v at first and when it started acting up its been at 13.2v since. Plenty of questionable wiring by previous owner that I plan to redo and tidy up. Could it be something grounding out or anything with the new alternator? Ive owned 3 others of these trucks with the 7.4 but all were auto trans. Sorry this is long, but wanted to get any info I could think of. I'm no novice to working on cars/trucks, but also not a pro mechanic, so I'll take any suggestions. Wife is starting to question my purchase, so I need to convince her this really is a reliable truck to drive our kids in!
