GMC Repair: Yukon XL starting problems, bosch platinum, yukon xl

Question
I have a 2000 Yukon XL, 5.3.  Recently, it began having starting problems and I notice it misses while idling.  It has no starting problem when cold -- only when warm.  Also, fuel filter is new and the fuel pump is less than 1 year old.  New spark plugs (Bosch platinum 2)were installed last summer but not new wires.  Have been using Gumout fuel injector cleaner every few fill ups and seemed to make some immprovement, but not solved the problem.  What is wrong?

Answer
I do NOT deviate from what the manufacturer recommends as far as replacement parts being installed. Especially spark plugs.

Could be plug wires, a vacuum leak in one of the many vacuum lines, a slight leak in a fuel injector or a malfunction in one of the sensors that in some cases will NOT illuminate the CHECK ENGINE light on the dash.


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