1997 Chevy Monte Carlo Missing and RPM

Last wensday my car was running great. All of a sudden last Thursday my car was hesitating when I would take off from a stop. And if the car was warmed up and I started it the rmp gage would go up and down then go to 0 and stall. Then if I was driving and would let off the gas real quick the rpm gage would go down way low and almost stall. I took it in to the chevy dealership and they said it was my mass air flow sensor so we replaced it. When I got the car back it did it again. So I took it back in and they said it was 2 of my spark plugs and one of my coils. So we replaced those last night. I drove this morning and it is 50% better. But after my car warmed up it hesitated again and when I took my foot off the gas the rpm shot down again. I am wondering if maybe my mass air flow sensor messed something else up in my car. I have only drove the car 10 miles since everything was replaced so I am also wondering if maybe it was so guncked up that I need to drive it more. My biggest problem is this car ran great a week ago. Please help me