My yukon has trouble starting. once I get it started it runs fine and once it warms up it will start fine. if I let it set for 4 hours I have trouble starting it again. I have no trouble lights on and it has plenty of power when it is runing.

check the spider.. EFI spiders are in intake and deliver fuel down intake runners,, they get old and crack and dribble causing un antomized fuel to leak into cylinders causing hard start a d drivability problems

Take back to the dealer.

If battery and connections are good (it's a big draw,different then other components).Because a bad connection or old battery can sometimes work the starter after it sits,doesn't make it .Some times a starter has a bad spot,thats whe you see some one get under and directly jump it.If buying a battery get at least recommended cranking amp size battery,Larger auto stores check battery no charge (bad joke). Its free google /bing who does a free battery test.Auto zons,pep boys,sears.May even be running a sale.Most switch out battery for fee (no charge*),*Hopefully you will laugh later.

Replace the temperature sending unit/sensor. This sensor tells the computer to put the engine into cold start mode and it then sets idle a bit higher and puts a bit more fuel into the engine to keep it running without having to touch the throttle. Once it's warm, sensor tells computer to go to normal run mode and it's done. No problem.

they had problems with the contacts in the ignition switch after they warm up they get better contact there for letting the vehicle run .

sound like your have the bad distributor, when you have trouble starting remove the distributor and have the auto part check it.

try changing your spark plugs they are prob worn out if not then try your leads?

have your evaporative emission control system check.sound like you have purge valve solenoid not working or vent valve control solenoid.have it scan.to see which component not working..reason your gas tank expanding. your fuel vapor building up pressure.your purge valve and vent valve open allowing gas vapor from charcoil canister. to be burn in the intake manifold to be burn in combustion chamber.

check to see if the EGR valve is stuck open if it is the vehicle will run fine once it is warmed up but as you will find that it acts as the choke for the vehicle it should not be to exspensive to replace but should fix your problem

My wife had same problem in 2005 yukon. Turn both temperture controls on dash all the way as warm as they will go, Wait about 1 or 2 mins and turn back to coolest setting. Cleared our problem right up. Do this with car running and air on.