1999 ram 1500 stalls after plenum repair

Replaced the plenum on my son's 99 ram last weekend. no issues with the intake removal and repair. start the truck, and it idled fine for about 10 seconds, then stumbled and died. restarted, dies at idle. If you you keep rpm it it will run, but as soon as it returns to idle, it dies. pulled throttle body from running truck, swapped it on, including IAC, MAP, and TPS from running truck. truck starts up, runs great. then we realized that we had left the vacuum line off the brake booster. plugged it up, truck immediately dies. pulled vacuum line back off, truck starts and runs fine. put finger over vacuum line to stop the vacuum leak and the truck dies.

I'm at a loss.....any suggestions.

Try sloooowly closing off the vacuume leak so the idle speed motor has time to adjust the idle speed back up.

When you had the intake off - did you clean the sludge out of it? If so - did the air temp sensor on it get replaced? It could be possible that a sensor got messed up - or not plugged back in when you're assembled. It is pain in the butt job - so something might have gotten goofed up.

I'll check both of those. the intake was actually a swap, used an intake i already had off, did the plenum swap on it, then pulled the intake off the truck, and swapped the repaired one on. did not change any sensors out, might be time to do that. also forgot to add, there are no codes or CEL

Whenever I have a problem right after I worked on something I go back over what I worked on to make sure I didn't cause the problem.

Ive just never had a vehicle run better with a massive vacuum leak than without one

I just did the plenum repair using a hughes kit two months ago. What a pain int the rear!

Retrace your steps - it is probably something stupid. As stupid as the design that puts that bolt on opening on the bottom of the intake........

We used the Hughes kit as well..... still hate the design... I tried to slowly close off the vacuum leak using my finger, say over 10-12 seconds. as soon as i fully closed it off, the engine died. I hate to throw parts at it. I also hate to pull the intake again.....but it's no good the way it is. maybe some more backtracking this evening will shed some light on the issue.

well, not sure exactly what fixed it, but it running like it is supposed to. Loosened up the distributor, wiggled it, then tightened it back down, hit the key, she started and idled great. no issues. thanks guys!

Was the battery disconnected?? After reconnecting sometimes the computer needs time ( even a few days) to reset itself...

It had learned how to run with the big vacuume leak in the intake, then the new vacuume leak, it just needed to learn to open the IAC more now there was no vacuume leak, usually the slowly closing the vacuume leak slowly gets it started learning.

Pretty much guaranty this is the issue. I have a 99 1500 also - have this issue quite often due to a crappy ground (gonna fix that some day !!)