I have a 01 yukon xl that has a wierd issue. maybe 3-4 time in last 3 months it cranks over but wont start. i will keep turning the key over several times and then it will start right up.anybody know anything? thanks

The only thing i can think of is a problem with the passlock system (theft deterrent). look for a security light when it does not start.

Once we had a suburban with a 5.3L that had almost 0 compression when it was cold. eventually it would start, but it would take a while. It set a SES (service engine soon) light with the standard misfire code PO300. It had sticky valves due to bad gas. It was a flex fuel vehicle and was run pretty regularly on E-85. We did an upper induction cleaning (BG fuel service) It helped, but didnt eliminate the problem, it just made the misfire and crank no start more random. we did two consecutive services on it and it cleaned up the problem. Im not saying that either of these problems are what yours is, but just making suggestions.