About a week ago i noticed my 99 F-250 SD started idle ruff even stall when I backed up the driveway once. then Fri night the "SERVICE ENGINE SOON" light came on. running down the road seems ok . But stopped at the light the engine revs up on its own.

Do they have one of those oxygens sensors on them and if they do where is it located on the truck? Any idea how much its going to cost me? thanks for help you can give me, Moose

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It could be your motor mounts, if they are broken or loose then your motor will rock forward at stops, causing the throttle cable to be pulled tight. and yes your truck should have O2 sensors on it if it still has factory exhaust. they are located after the manifolds and they look almost like spark plugs. good luck man!!

I looked at the air filter pretty dirty(I live in Arizona). I only see one sensor but I looked up the part on carparts.com and they say it requires two. Any ideas were there at I see one just before the collector just after manifold drivers side but I didn't see one on the other side. Also what is the sesor just after the air sensor. thanks for the help

Check the codes first, is your truck desiel or gas. If its gas then it sound like a ox2 sensor to me.

codes ok

how do I check them. do I need a special tool or do I have to hook it up to a diagnostic computer. I'm planning on a tune up in 2 weeks. the truck has 146679 milesas of today

Yes, you do need a special scan tool, but Autozone has this 'free scan your code thing going on'. I wouldn't buy anything until you have troubleshoot the cause of the code/s first. Also, there is a idle control valve that when it gets dirty enough it causes this same problem. Its easy to fix, just remove it and clean it with carb cleaner. I'm now guess that your vehicle is gas and not diesel.

were do I locate this idle control valve. I looked at the truck today seems like its starving for air. making a sucking sound near the intake area. I'll have to check out the autozone thing. thanks I'll let you guys know what happens:D

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It will be near the trottlevalve. It will have a bypass of the buttlerfly plate. look just above the cylinder heads and you will find it.

HI GUYS I HAVE AN 99 FORD F-250 LIGHT DUTY TRUCK WITH THE SAME PROBELM RUFF IDLE AT TIMES...NO CHECK ENGINE LIGHT COMES ON OR ANYTHING LIKE THAT..I HAVE TAKEN IT TO FORD ONCE BEFORE WITH NO CODES. SO WHAT DO I DO NEXT...HELP PLEASE

lordswork I'm sorry i never went back to this site to tell everyone how I fixed the problem on my truck. I took My truck to the local dealership and they ran diagnostics on it. Come to find out that the PCV valve had cracked and was causing a vacuum leak. Once replaced the truck is running great. Good Luck to You