low lopey idle

[DBogo]

alright my truck starts and runs great, although after i drive it for a while it will idle slightly low, people told me to raise it up a little so i did, its right above the 750 line now, it still does the same thing, i start it it will run right there smooth as silk after i drive it for a while the idle will drop just to that line and if you give it throttle to bump it back up, it is real shakey and lopey all the way up till about 1200 rpms, im not sure at all whats causeing this but im getting sick of it, also i put my plate in and it will blow smoke rings out, im not sure if this is a problem with my injectors or what, someone said compression problem but it dont use an awful lot of oil, i dont know if these two things are connected but anything to help would be great

thanks guys

 

[moneymaker44]

could be sucking in a little air in the lines

 

[DBogo]

but why woudl it be only once its run for a while?

 

[DONK78]

Where is your timing set? and have you checked you fuel psi?

 

[DBogo]

timing is where it came at, which i beleive is stock, and no i havnt checked my fuel psi, but all of these things why would they only happen when it is hot?