89 oldsmbile 98 3.8

i have changed the crank sencor cam magnet and sencor air filter ok here is the problem i start it runs great well about 30 mins to a hour later it starts stumbling then about 15-20 mins later if i let my foot off the gas it will die but it will start right back up but then put it in gear and it has very low power and in park if i hold the gas peddle down a little it will rev up and down and pop a little but when it is cool it runs great when it warms up it will stumble and die but will start right back up no codes but when it gets warm it act dumb please help me

Start by checking fuel pressure at the rail, look for about 40 psi.

o i forgot i run it up and down the road today about a hour when it started to act up i got it back in the yard to check if there was any codes in the computer i poped the hood it felt like the whole front of the car was hot the fenders the metal where the hood latches and i think the water was pretty hot it was gergling a little