Just looking for ideas. My 5.0 keeps missing. It will run fine for about 5 to 10 miles than its starts to buck and the tranny shifts way to soon at low speeds. I've changed the fuel filter,wires, plugs, cap and rotor but nothing seems to help. My buddy thinks it's an ignition problem but before I start replacing all,kinds of parts I was wondering if anyone else has had this problem. If I shut it off for a few minutes it runs ok for a few miles than starts all over again and if I drive far enough it will clear up and run fine. It's got me baffled. Some good advice would be nice. Thanks in advance.

 

Need more info: Is the CEL coming on at any point? Have you tried to pull the codes to see if anything is logged in the CPU? If codes are present, what are they? Any type of black smoke out the tail pipe? Have you checked to see if there's any fuel in the vacuum line connected to the fuel pressure regulator as you may have the starting of a breeched diaphragm. Have you tried to manually shift the tranny to different gears to see if the issue clears? Plus, especially this time of year, do you have good clean battery post connections?

 

Thanks for the reply. The CEL does not come on and I don't have a code reader. I changed all the vacuum lines and there was no fuel coming out of the line to the fuel pressure regulator. I put a new battery in about 6 months ago and the connections are fine. There is no black smoke coming out of the tailpipe. I personally think it's an electrical problem. I've tried running it with the egr valve disconnected made no difference,also tried running it with the mas sensor disconnected, made no difference. Tried disconnecting the battery to reboot the computer, made no difference. Tried running sea foam through both gas tanks several times made no difference. Thinking it could be the ignition module or the the ignition coil or even the distributor itself. If you have any more ideas it would be greatly appreciated. Thanks.

 

Might try doing a range sweep on the TPS to rule it out, a voltage drop out could cause bucking and certainly incorrect shift timing..

 

Thanks for the information sharing ...