I asked this question a few days ago but did not hear a peep from you. Without a donation, I guess it takes a few weeks, eh? I have a 1998 GMC 3500 van with 140,000 miles on it. It starts ok the first try, but it seems when it gets warm it is sluggish in starting. I replaced the plugs, the fuel filter, and had an injection cleaning, but it still does it. What could be the problem?
You may want to test the fuel pressure to ensure that you have good pressure, also while you have the tester attached to the fuel rail you can remove the vacuum line from the fuel pressure regulator and your fuel pressure should increase, if it doesn't then you probably have a fuel pressure regulator that is starting to go bad. Good luck