On my 93 F150 XL with the 5 liter 302 it idles really high and I dont know what to do. I have the idle screw out basically and when i put it into drive it will do about 30mph without even touching the gas. I just installed a tachometer today and it is ideling at about 1100-1400rpm. I dont know what to try hopefully you guys can help. Thanks

 

1- put that screw back where it was. never mess with the screw. its not an idle screw, its a throttle plate set screw and it keeps the throttle plate from spinning all the way until the spring has no more tension on it.
2- check for a vacuum leak. mainly check the intake gaskets.

 

I'm not really sure where the screw is supposed to be, it was all the way out when i got the truck. I went through all the vacuum lines and replaced all of them last spring so I know the lines are good.

 

you sure they were all put in the correct locations? and check the intake manifold gaskets. they can leak causing a vacuum leak and that causes a high idle with speed density systems.

 

Yeah there put on the correct locations. I did each line one at a time and followed the diagram plus my dad was watching to make sure it was right too. Whats the best way to check the manifold gasket?

 

well one way is to hook a vacuum gauge onto it and see what the readings are in "hg(inches of mercury). should be between 17 and 22"hg. if its got good vacuum then check the timing- pull spout connector and hook the timing light to it, and at operating temp it should be set at 10*. if the timing has advanced then it can cause a high idle too.