i recently purchased a 98 ram 3500 van. I havent driven it much. it had 125,000 miles on it when purchased. today my father drove it about 100 miles to pickup some material and the alternator went right when he got to the warehouse. luckily he was 2 blocks from a repair shop who installed a new alternator. afterwards he was driving and all of a sudden the van's idle dropped and it has minor misfiring and then came back to normal a few minutes later. when he returned home i hopped in, after cooling down, and same thing the idle dropped way down, the battery gauge lowered a bit as well as the oil pressure but then a few minutes later it just came back to normal and ran fine for the entire trip. It seems that everytime you stop and shut the van off then go to leave it does this. it happened 3 more times to me. And 1 time it even stalled out. but once it comes back to normal it runs fine the entire trip only at startup theres a prob.Does anyone have any ideas im going crazy?

 

Not a professional but I would check all grounds.

 

Did you check for codes?