I have a 2000 f-250 with the v-10. Over the last couple weeks I have been having problems with a surging idle in the truck, CEL was on and I ran the scanner on it. It told me that the o2 sensors were bad. Went out and bought them and put them in and reset the computer ( i replaced both with new ones, my truck only has 2 ). The surging idle was STILL present but not quite as bad but the CEL never came back on so I figured that it was just the IAC valve. So today i went to the truck pulls and pulled it like i do every chance i get. Pulled it in the 7000 lb weight class and it ran absolutley awesome as the surging goes away the instant the truck comes off idle. Made the pull and got the second longest pull of the entire day over ALL the classes, so the truck ran great. Unhooked from the sled and went back and shut the truck off and waited till my next class to come up. Half hour or so later my second class the I was pulling in was up ( 7500 lb ). I went to my truck started it and other than the surging idle it was running fine. I hooked to the sled and made my second pull. I always run the truck rpm up around 4500. Right towards the end of the pull as the sled was getting really heavy and the truck was working hard right as the truck could get no further and was just starting to spin the truck seemed to lose all power and would barely spin the wheels. When the guy waved the red flag for me to stop trying I let the gas off and the rpms dropped to almost nothing for a split second then it stalled completely ( the truck is an automatic ). It however started right back up, but now is running REALLY bad. Since the truck is one of my daily drivers I drove the truck there I had to drive it back home running the way it was. On the way home it only seems to be running on 8 or 9 cylinders at lower rpms and for some reason there is this odd smell coming from under the hood and into the cab that can only be described as a sulpher type smell like someone put a match out. Higher rpms the truck SEEMS to have all the power as normal but i really wouldnt know because on the road i rarely EVER have the rpms over 3000 but the misfire IS still there but not as severe. The CEL came back on on the trip home so when i got home i ran the scanner on it again and now its telling me that the truck is running EXCESSIVELY lean on BOTH banks. Im at a complete loss because I never had a truck do that plus i never had a truck that was emitting a smell like that. I REALLY need my truck this week because im moving and i need it to pull my trailer ( i know i know i SHOULDN'T have pulled it this weekend because i DID need it ), so ANY help would be appreciated. Thanks ...... and a little side note .. how bad is it to drive it running as lean as it is, because i really need it, but its really unhealthy for it to the point where i might blow it up, i wont use it. Thanks again.

 

Those codes can be tough to figure out sometimes, basicaly the ECU is saying "that ain't right" but electrically everything is fine and within allowable parameters. Look for any vaccumn leaks or unmetered air leaks first. If you come up empty try unplugging the MAF and see if it runs better on its default fuel maps. If it does that would suggest the MAF..

 

As Chad149 said, check for a vacuum leak. Since it is BOTH banks, check the PCV valve hose where it goes into the intake. I had the same code and that hose was my issue. If you find the hose is cracked, don't replace it with the same one because it will also crack some day. Just cut an appropriate diameter fuel hose to about 12-16 inches long and use that. It will loop out and around, but it will not have a tight bend that causes the cracking.

I wouldn't drive it HARD when it is running lean, but if it is the PCV hose then it will only take 5 minutes to fix.

 

thanks guys i will give those suggestions a try when i get off work tomorrow as i work a long day today and wont have time when i get home tonight