I have a 87 F150, 4.9 that idles too high 1800 rpms. This truck sat for about five years before I got it. Help.... thanks

 

check IAC valve on the throttle body, and the TPS. maybe run some throttle body cleaner through it. does it do it all the time, or just when its cold?

another thing, since this truck has been sitting for so long, is to check the vacuum hoses. all of the hot-cold-hot-cold of everyday temperatures and just sitting could easily crack a hose, causing a vaccuum leak somewhere, also causing a high idle.