Hi all, I'm new to this forum. I have a 1993 with the 5.0 and it has some pretty high miles on it. (199K to be exact) Anyways, I'm having a problem with the idle. It stalls sometimes at a low idle. While driving it runs fine 3/4 to WOT, but anything under that it surges and hesitates. When it first started it was only doing this when I was on the front tank, so I switched to the back one and it was fine for a about a week and a half. Now it does it with both of them. I know it is burning rich, because it stinks, and some black smoke it coming out the back. The spark plugs and exhaust is all full of carbon build up. I changed the oxygen sensor, full filter, and did compression check. On the compression, the lowest cylender was 140 and the highest was 165. It is eating gas like crazy.

Anyone have any ideas what my problem is (besides the fact that it is old and has high miles)? I'm thinking it is a throttle position sensor, but am not sure. Any help is appreciated.
Thanks!

WADS

 

anyone have any ideas?

 

I had the same problem with my 98. It is a 4.6, but was doing the same thing. I narrowed it down to the plug wires or the coil packs. I replaced both, but you could troubleshoot to see which it is on yours. If the wires are stock, they may be the problem. I hope this helps you because I know how bad it sucks for your truck to run like crap.