I just bought a 99 f250 with a 5.4 the coils; injectors, fuel pump and filter had all been changed and was running great. Now it is having high and low idling problems I had it checked out and they told me it was my cam sensor. Changed that and its still doing the same thing and it feels a little sluggish.

 

Check your Idle Air Control Valve, behind the throttle body. I believe you can clean your year's model (not mine) with some carb cleaner, but i would just replace it as they are cheap.

 

Possible vacuum leak Or IAC..

 

the IAC is new.it runs good for a while then it will start trying to stall as im driving.i can turn the key off and back on and it runs good again but then when i stop it will idle high.i dont think it would be a vacum leak cause if i let it run for a few it will idle back down.

 

Have you hooked it up to a scanner to see if there are any pending codes?

 

Fuel filter new also? Pcv valve? Most likely a vacuum leak of sorts.

 

not after the cam sensor code.

 

Also try cleaning the maf.

 

Throttle position sensor?

 

Im thiking it might me the TPS also. cause i tried cleaning the MAF and still the same.(somewhat) now when its trying to idle its trying to kill then idling back up.when i pull the plug on the TPS the idle drops. so guess that will be the next thing..lol..its always something with these damn trucks.. just hope its nothing major sence i just bought this one.

 

I checked the codes today and got p0122,p1100 and p1000.

 

Clear the codes and see what happens as those might have happened while you were fooling with it... Maf intermitten....HMMM

 

I cleared the codes and it's idleing a little better but still feels a little sluggish so I'm gonna have to pick up a new sensor this week

 

I wouldn't pick up anything yet..Clearing the codes wouldn't have fixed it. It just had codes because you were working on it. See what code comes on by itself...TPS will set a code if its bad plus you can test it with an ohm meter or a scanner. I can read the value of it at at any angle on my scanner.


Dick

 

After dealing the the TPS, if you are still having issues I would take it to a Ford Dealer or reputable shop, have them perform a power balance test to see if its a ignition/cylinder problem, and which one.