Do you know if they have cleaned the throttle body or reprogrammed the engine control module with the latest calibrations for this idle concern? Also, regarding the hard start has the fuel pressure regulator vacum hose been checked for signs of fuel indicating the diaphragm inside the regulator is leaking fuel into the vacum?
The fuel pressure regulator is easy enough to check...locate on the left side of the engine, disconnect the vacum line and if any signs of fuel suspect a faulty pressure regulator. As for the cleaning the throttle bore and plate along with reprogramming the engine computer that all needs to be done at a GM dealership as GM software and Tech 2 scan tool are utilized.
Upper Intake Manifold Sight Shield Replacement (4.8 L, 5.3 L, and 6.0 L) Removal Procedure
Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.
Tighten Tighten the engine sight shield retainer bolts to 5 N·m (44 lb in).
Notice: Use care when installing the engine sight shield to avoid contacting the manifold absolute pressure (MAP) sensor wire harness connector. Loss of engine performance or engine damage may result.
Tighten Tighten the engine sight shield bolt to 10 N·m (89 lb in).
Fuel Pressure Regulator Replacement Removal Procedure
Ok well thank you for your help. Unfortunately, I am visiting my family and my truck is back home across the country, but I plan on taking your advice when I get home in a little over a week. I am still wondering because I have had this problem for a while now, is there any possibility they could have cause some sort of greater damage? Like if the fuel pressure regulator has been faulty for all this time could it have caused some greater problem that just hasn't shown itself yet or if its the throttle bore and plate, can it have caused other damage? I am planning to take it to a GM dealership but I would like to have some kind of idea of what things will cost or roughly how long each of those things (cleaning the throttle bore and reprogramming) will take? The only reason I ask is because if it is going to be real expensive I am going to need to save up a little before I get it fixed, and the closest dealership to me is about an hour away so I can't just run up the street and get an estimate. I realize rates vary but I'm just looking for a loose, ballpark figure. Thank you so much for your time and your help. I am going to accept your answer, but I was just hoping you might be able to help me out on these last few questions. Thanks again, have a wonderful day.