Hello, am new to forum, am not a mechanic but am facing a confusing situation I thought some members of this forum could point me in likely direction. 1998 Dodge Ram 1500 van, 5.2 liter automatic, 170 k, has always run great with minor exceptions, problem started a couple weeks ago. I have only experienced this problem after running 30+ miles at freeway speeds. When coming off freeway, ie slowing down, truck will sometimes stall at stoplight (and sometimes not). When it does not stall, warmed up idle speed seems fine. I have taken to shifting into neutral when approaching stop light or slow heavy traffic to avoid stalling, After stalling, car will sometimes start fairly easily, but sometimes it won't. Will pretty much always start after a minute or so rest, but this is not always convenient in a turn lane at a light or many other places. Yesterday for the first time I felt the engine missing at freeway speed, just a quick jerk, then back to speed, but slowing down on long ramp off freeway completely stalled going about 40 mph. I was able to coast to the shoulder, Would not restart for a couple of minutes, when I could finally start and get on to city street it stalled several times before I could get to a safe parking area. I was 30 miles from home, started making calls to rental places and friends, but after maybe 20 minutes decided I'd see how far I could get, truck started great, drove 30 miles at freeway speed, did not stall getting off freeway or at stoplights. It was raining and fairly cool out. One person thought I might have a problem with bad fuel but I filled up before this last excursion and added injector cleaner. Any ideas out there how to trouble shoot this?
Thanks, dougmck

 

The stalling could be the Idle Air Control (IAC) valve. It's mounted on the back of the intake and held on by 2 star screws. This valve controls the idle speed and when it gets dirty it gets sticky. Remove it and clean the plunger area good with carb cleaner and also clean the hole it goes into using Q-Tips. The jerking on the highway and not starting for several minutes sounds like the crankshaft position (CKP) sensor is on it's way out. Buying an aftermarket one is less expensive but many have reported random misfires with them. An OEM one from the dealer is the best one to get even though it's more expensive.

 

Thanks, seems like a good place to start, will give a try. dm

 

I had a similar problem with a 1979 Honda Accord. Usually happened when it was about 40 degrees outside when I left for work in the morning. It would start perfectly, run fine for about five minutes and then start to get weaker and weaker and then stall. I would get out and check the carb, after removing the air filter, and everything looked normal.
Finally I stopped driving when it first started to get weak, jammed something against the gas pedal to keep it running, took off the air filter, and there it was. The carb was full of ice.
The other times, it had time to melt the ice before I could see it.
The vacuum line had broken and the carb preheat didn’t operate, thus the freezing.
I hope this helps someone.