So I recently bought a 2001 dodge ram 1500. 318. Only problem I've had until recently is the tensioner pulley locked up which was no problem. The other day I went to the store and it drove fine all the way they until I went to park. As I slowed down it started idling down and came very close to dying. When I came to a complete stop it idled back up and started running fine again. When I left however it idled all over the place and I couldn't get it past 7mph. The next day it ran just fine. Drove her for hours with no problem. Then today I went to leave work and it did the save thing but I was able to get to speed with her rpm's going all over the place. I noticed that every time I touched the gas it would make a sound like compressed air escaping in a quick pop. It was raining every time this happened. So I don't know if the rain has anything to do with it or not but I would really appreciate any input.

 

Welcome to DF!

Check and see that the seal at the back of the hood, that runs over the engine, is still there. water tends to drip down onto the distributor cap, and cause issues.

 

I can't believe I didn't think of that, I have to put the seal back on almost every time I pop the hood.

Thank you! I'll let you know if that helps =)

 

Isn't it always the simple stuff that comes back and bites you in the keester?

 

Well. I changed the cap and rotor. No difference. I'm going to try the coil next. After that I'm not sure. Could a bad o2 cause this?

 

How's that seal?

Gotta be something that doesn't like getting wet. Most of the stuff is fairly well protected, and the O2 sensor just wouldn't care.... unless there are some wiring issues?

 

That's a screwy problem you've got there. Idle problems without misfire in humid conditions are often caused by a hanging IAC, but I've never seen one cause the whole range of symptoms you've described. Were it mine, though, I'd give it a look just the same. Most of the time all it takes is a good cleaning, with proper care taken to avoid roughhousing the pintle.

 

Replace the spark plug wires. When they wear (yes, plug wires wear), moisture causes increased resistance and inhibits proper plug fire.

 

At night, take a spray bottle full of water and as the engine is idling, spray a mist of water over the spark plug wires. If you see some arching, they need replaced. If it starts acting up with those symptoms, you're on the right track.

I had a similar problem with a Subaru in rainy humid days only, did the water bottle method, found it was the spark plug wire arching and swapped them out, problem solved.

 

In my experience it sounds remarkably like the IAC, and the raining is just a secondary coincidence. If it's idling very low and sounds like a major vacuum line came off...I'd spend the 45 dollars and change the IAC.