Higher idle? Where do I start?

[zieg85]

OK, here goes... My 1985 C10 with 119K miles and a 5.0L automatic is idling to high when warmed up.  I have not dove into it other than verifying that the choke is open fine.  Cold start seems fine, pedal to the floor to set the choke, a few revolutions and it starts right up.  Idle seems fine when cold and first start, truck will almost go into gear without dying out like the choke pull off is opening it up a tiny bit to much.  As it warms up the idle goes up and stays up, maybe 1200 rpms in park.  I put it in gear and it seems about right as far as I can tell as it doesn't take off like it would be if the idle was to high.  I know numbers would be helpful as far as rpms go but I am just setting up a plan of attack and want to bounce ideas around.  I know first thing is to make sure I am off fast idle cam but I really think it is timing related.  It also may be a vacuum leak?  Input please???

[VileZambonie]

If it's coming off of the fast idle cam, check for vacuum leaks.

[zieg85]

Thanks Vile, as I was typing and thinking that seemed a possibility to me as well.  It is supposed to be in the upper 40's tomorrow, I'll check it out tomorrow after I get home from work and report my findings.