hesatate and stalls at times

I have 1995 olds cutlass 3.1 engine. It will hesitate at times and will stall ones in awhile. Can go for days with no problems, then well hesitate or stall 1 or 2 times a day for 2 or 3 days then clear up and run good for days before acting up again. Trouble codes #75- EGR solinoid #1, #76- EGR solinoid #2 & #77- EGR solinoid #3. I replaced the EGR and solinoids. The car still hesitates and stalls!! Any sugestions will be helpful!!!

Thanks for your time.
John