intermittant problem, start car runs fine drive awhile and kill it come back later 15 min.-1 hour car turns over and starts runs very rough and dies this goes on for sometimes 10 tries and then finally starts and revs up to around 1500 rpm and goes down to normal idle and runs fine until killed again. doesn't happen every time. koeo fuel pressure 24 -koer fuel pressure 34. no mil codes. any ideas what could be going on ? also sometimes stumbles going up some hills ,but not all hills and not always same hills. any help would be appreciated

Fuel pressure is low. But before you do anything pull the vacuum line off the fuel pressure regulator and smell it. Do you smell any gas?

already changed the regulator, new plugs and wires also

Then I would be looking at your fuel pump. Pressure should be around 48 KOEO, and around the same KOER.

how long should it hold pressure in system before it bleeds down?

changed fuel pump, now pressure is up past 40,time will tell if that cured hard start problem , still stumbles some on some hills so didn't fix that problem

sometimes ign parts when going out start to do this too. since you already did the plugs and wires i would suspect coils. try this test but you may not get anything they tend to get worse as they get hot

https://www.gmforum.com/showthread.p...ight=coil+test

You can use a heat gun to heat up the coils.