Buick Le Sebra 1995 3.8 with 135.000 miles

On a Buick Le Sebra 1995 3.8 with 135.000 miles: there was an engine hesitation. I changed the 3 coils and it stopped. The check engine is on and off (although lately on all the time) for the last 30.000 miles... And no one around has the instrument to check the old 1995 computer. Than after the car was sitting for weeks it start hesitating again, and on a cold start the engine will run to 3000 rpm and only after a few minutes when I shut her off and start again – she would go to the normal just below 1000 rpm– I changed the Oxygen valve today and on a start she run again to 3000 and there was improvement on the hesitation (almost disaapeared) and while driving she whent down to normal rpm. However after arriving she will not start hot – it will catch a spin but then die. She will start cold with 3000 rpm. I didn’t move her. What is the problem? Can it be the EGR valve or the throttle position sensor or what?