Every 6 seconds my truck idles up from about 500rpm to about 1000rpm. I have replaced the IAC valve, TPS, airbox gasket. I also had a bad vapor canister that was clogging my vapor purge valve. I replaced the charcoal canister and blew out the valve and line. Any one else have this idle problem and get it fixed?

 

Have you ran a code scan on the truck? If so were there any codes? If so what were they? You could have a vacuum leak some where. You could have a sensor that is faulty. There are many variables that could cause your problem.

 

That is what is driving me nuts. I have no codes. I will get it scanned tomorrow and see if there are any on there. My check engine light is not on. Runs great driving down the road. But every 6 seconds driving I also feel a change in the rpm. Could it be a plentum leaking?

 

maybe you got a bad tps, it won't hurt anything to return it. or you can check the voltage output with a multimeter using the instructions in the haynes manual.

 

This is going to sound really dumb, and I don't know the name of this right off the top of my head, but there is a rubber line on the front of the TB that I've had crack and do the same thing. I cut the cracked piece out and pieced in a new piece of rubber and it works just fine.

 

I have a plastic vacuum line on the front of the TB that has a rubber piece of hose connecting it to the TB. This rubber hose looks cracked but I didn't see where it could have been cracked all the way through but I think I will replace it anyway.

 

Yea, that could be doing it.

 

I had a friend of mine tell me to check and see if it may be my o2 sensors that are bad. Could this be causing it to idle up every 6 seconds? Whatever it is makes my IAC valve open and close every 6 seconds. I was just wondering if a bad o2 sensor could tell the computer to allow the IAC to open letting more air into the throttle body.

 

replace the plastic vacumn lines with rubber , that's just a good practice .

It's not the plenum or mine would be doing it too (hughes plate kit in the garage)

I am going to refer you to this thread https://dodgeforum.com/forum/2nd-gen-ram/216677-fuel-pump-or-fuel-leak.html where I have a detailed instruction to clean the PCM connection . You could drain the power , unplug and simply reconnect , this should improve the connection before going through a tedious process . Poor connection should be ruled out before spending more money

If you want to test the O2 sensors (upstream) unplug them , the computer will run on preset settings , this will cause a CEL that will go away or be cleared once plugged back in . Doubtful you'll see any changes from this .

It would be nice to have a vacumn guage and a fuel pressure guage hooked up to know the readings while it surges

 

i don't think o2 senors would have anything to do with idle surging.
mine was doing that surging thing from 800-1500 up and down. it was the TPS.
the rubber hose in the front of the TB is to the MAP sensor. if its cracked replace it.

for all those things you replaced, if they had "no effect", then it rules them out. getting a new bad item that does the exact same thing as the old bad item is very unlikely.