I am having an argument with a buddy here about what is the usual problem for a 5.0L to have that good old hovering idle... up and down. HO or not (truck) they all do it.

i'm saying IAC, but he says some solenoid...?

 

from past experinces i thought that if the solenoid is hooped, then the vechicle will not run at all.

 

there's a ton of things that cause the wandering idle....first thing i'd do is clean the IAC. after that there is a black and a white connector right behind the intake...pull them apart and clean them up. if it's still idleing rough i'd start thinking o2 sensors.....wandering idle is one of the problems that can take forever to track down on these cars...

 

Also Could Have A Vacuum Leak Or A Combination Of The Throttle And Tps Not Set Up Properly.

 

HA, i took the IAC off, cleaned it and its fine now... it had a good carbon build up in it

 

The IAC is often referred to as the Idle Air Control Solenoid............

 

I had this problem with my 88 Cobra 5.0lt, I cleaned the IAC, that did nothing, so I replaced it with a new one and still no change, I later figured out it was a shitty head gasket...sucking air when the car warmed up..ran like for a while but fixed now.

 

it could have a vacum leak and that would cause wandering idle and might cause the map sensor to change peramiters makeing it run rich or lean.

 

Cleaning the iac is probably a safe bet and couldn't hurt.

 

ive had previous problems with my old 5.0l and checked the iac and didnt do anything...turned out it was the maf ...by the way im a newbie here..first time posting long time driving