My truck dies as soon as I let off the gas and has an ugly rattle noise that seems to diminish as I give it more gas. I had codes 172 and 173 and changed o2 sensor, did not help. Was driving the truck with two feet for the last month and horrible gas milage. Was fine when I am moving but if I stop it dies. Now with snow on the ground the two foot thing is no longer a safe option. I dont know if it is related but I also could not move the shifter and used a little too much force (got frustrated) and busted something in the steering column, but that has been replaced. What can I try next. I also had codes 628 and 634 but I think they were related to my shifter before I busted it.

 

Well after reading everything I could find on idle in this forum I cleaned the IAC valve and it idles now but I still have this noise like its a diesel engine. Coincidence or is my engine done. Is there something in the emission controls that would cause it to sound like this?

 

I would CHANGE the iac motor.Cleaning always doesnt work.