new question, but a strange one!
 

O.K. heres a strange one for you. When the truck is in park and idling at around 1200RPM, if I put my foot on the brake it idles up to around 1500 to 1600RPM. If I take my foot off the brake it idles back down. Any ideas??

Power brakes? Vacuum leak somewhere?

Anything under the dash making contact with the acc. pedal?

if its got power brakes the booster is probably leaking plug the line to the booster and see if that fixes it. 1200 is damn high for an idle though normal idle is around 700rpm

It has power brakes. I will check that tomorrow. I know the idle seems high, but I was trying to adjust it based on the sticker in the engine bay. It actually says to adjust it to 1500 RPM in Park, and 600 in drive. IF I adjust the idle down to 800 in park I get like 350rpm in drive. For some reason I can't adjust the park idle and the drive idle seperately on the edelbrock 1406 I have. At least I haven't figured it out yet. When I adjust the idle screw it adjusts both park and drive idle. When I adjust the mixture screws I get the same results. Any suggestions?

sounds like you have a major vaccum leak. it should be no higher than 800 in park drop to about 650 in drive or so

there is no seperate adjustment for park idle and in gear idle it should never drop 500 rpm between the two. maybe 200rpm tops nothing more. the 1200 on the stick sounds like the high idle when the choke is engaged

My truck does the same,it idles at 700 in park apply the brake and it idles up to 800 pull it into gear and it idles at 600. I have a 670 holley and can't find any vacume leaks at all. And the brakes are real sensitive.