My 86 f-150 5.0L EFI runs smooth in park or idol and is rough when in gear and stopped. It also doesn’t like to start. Or I should say it turns over, starts, idols real ruff (almost like it’s not on all cylinders) then dies out. It starts right back up after and usually settles into a smooth idol. Just looking for some hints as to where to start to trace this problem too… By the way a diagnostic test comes back as fine (11).

 

try cleaning the IAC on the thottle body They cause a lot of idle problems. A new set of plugs and wires wouldn't hurt either

 

Do you have a C6 tranny?

 

I would think it would be the first thing Bremen said. Maybe number 2

-Matt

P.S. Bremen: Again with the avatar?!?! Come on!

 

You might want to take a look at the motor mounts, cause a boken one can cause it to be rough in gear and smooth in park/neutral

 

Thanks for the suggestions, but the plugs and wires are new...

I went and got the throttle body gasket kit and am going to take it off and do a full clean on it, the IAC and the EGR sometime next week. I also heard of a module on the tranny that could be causing a vacume leak that might be a problem so that is going to get looked at also.

By the way i have the automatic with overdrive on the tranny... Not sure which one... I'll check either on the tag or when i am under it next time....

 

If you look close, it may be a vaccum leak someplace. What codes are you getting while running?

 

the only codes i have gotten are 11-10-31. Those are KOEO.
So it says everything is working fine...