I just completed changing the spark plugs and wires on my 97 4.6 (91K) for the first time. Not to bad of an ordeal, thanks to all the helpful threads here. Big improvement and seems much smoother! I only had time to drive it for a few miles, but at every stop, the idle would drop down to a near stall just for a second or two and then return to normal. I read somewhere that since I had the battery unhooked for several hours, the computer has to re-learn the settings and this could take a few starts? Could that be whats causing this? Other than that, I'm just going to go back and make sure I didn't leave anything unhooked. Thanks for any help!

 

Check for vacuum hoses that are unplugged or were damaged.

Check to make certain the IAC didn't get unplugged.

The idle speed reset logic should correctly control the idle within several drive cycles if there are no other faults.

Steve

 

Did you let the truck idle for a few minutes after you restarted the truck?

You might try resetting the PCM again and then when you reconnect it, let the truck sit and idle for a while (I think you are supposed to do some with A/C and some without).

 

Thanks for the replys. I had the chance to drive it a few more times and it still idles down to near stall at stops. I went ahead and reset the PCM and let it idle for 20 minutes (10 with A/C, 10 without) and it didn't help. I have noticed it does better with the A/C on though. I guess I'll go through a couple more drive cycles and see if it improves. I assume a drive cycle is from a cold start?
Thanks again for the help.

 

Try cleaning the IAC (do a search, many threads on it).

It's a 5 minute job for the 4.6L.

 

not being smart here or anything but did you place a wire on the wrong plug so that it is out of time? i'm sure you would have an error code come up but you never know. just a suggestion.

 

No, it's definetly nothing to do with the plugs or wires. I went ahead and cleaned the IAC and noted some improvement. I may go ahead and replace it as it is the original. Thanks again....