I have a 99 dodge ram 360 sport. I've had a problem with it running rough for a year now. i would call it a misfire. when its in park it will eventually shut off. it will start to shake like its out of gas. I get an awful smell. If the heat or ac is on it will shut off then truck will minutes after. i replaced the drivers side head (had a burnt valve and was told it wouldn't seat right), sparks plugs, wires, 7&8 fuel injectors, rotor, cap, fuel pump with fuel filter, 02 sensors, completely new dual exhaust from head back including cat. im probably missing some. a friend of mine unplugged 4 of my fuel injectors on passengers side and my truck started up and ran the same. i have no check engine light on. I'm confused!!!!

 

Being if you turn your AC on I could understand being it's an extra drag on your engine but heater? That can only mean electrical. Have you had your Battery and Alt checked? Check for bad grounds positive leads and rather your charging system is working properly.

If you do not have enough Amps then it wont run right.. or a low battery.. I would check them out on the premise of the heater causing the issue being that is electrical pull.

 

To start you might want to pull the TB and check inside the IM for oil pooling. If never replaced you can count on the plenum needing replacement. Next the IAC might need to be replaced but low on $$ you can just clean it as well as the it's port in the TB while you have it off to ck the IM. Many times the CEL won't come on until the very end of a part, so it could be one or more on the way out. The neg bat cable should be removed when doing work on sensors...

 

+1 check the intake manifold plenum. its the reason why you had to replace the cat, and more than likely the head too.

 

I did replace iac. There's no oil deposits in the IM. Its a new battery. The guy I bought it from said it was the pcm connection on the firewall. I cleaned it and it made zero difference. It shuts off with the AC and heat turned off too while in park.

 

Time to check grounds if you didn't already if you did check again..start checking sensors with a meter..BTW, did you change the crankshaft position sensor?

 

That is weird, runs on only four cylinders and no CEL.

 

Possibly the connections in the steering column? I grab harness underneath dash and push up towards steering wheel if things start working again I know I need to pull covers on steering column and check connectors.

 

That's what I was wondering, should have went on as soon as the FI were unplugged right

 

I didn't change crankshaft position sensor. The CEL did come on when I had 4 of the injectors unplugged. It stayed on only for short time.