I have a 2004 Bonneville SE. I drove it Saturday about 50-60 miles came home, parked it in the driveway an hour later wouldn't start. After about 4 hours it started like a dream. Took it to the mechanic (ran 70 miles an hour all the way) now it won't start at all. Replaced fuel filter, has great fuel pressure, EGR valve not stuck, also tested the TPS, all plugs are firing & not wet, Oh and it not showing a check engine light or throwing any codes.
I do not want to just throw parts at this car & hope that something fixes it...PLEASE HELP
125,000 miles on it too

OK, you have spark, and fuel pressure. But you don't know if the fuel is leaving the injectors. Do you have a VATs on this car? Try a different key. Can you hear the injectors click when it'* turning over?

Thank you for your help. We put a fuel pressure gauge on it last night and it only has 46# of pressure on the line. Being as it is multiport it needs at least 60# so we are changing the fuel pump.