89 Grand Am stuttering mostly at high speeds

89 Grand Am
70,000 miles

My Grand Am has had increased stuttering lately, and mostly seems to occur while on the highway at higher speeds. To describe it, it's kind of like a hiccup that the car has for a split second where the engine cuts out, and then kicks back in. These "hiccups" tend to occur in groups, where it might not happen for a few miles, then 4 or 5 times successively. About 3 months ago the problem first occured while driving at relatively lower speeds (around 40 mph) and the engine died on the same trip that I first felt the stuttering. It required me to give it a little gas while turning the key in the ignition to get it running again, but then ran fine with none of the stuttering again until now. This time I had felt the stuttering, but it was going on for a few weeks before the car once again died. I took it in to a mechanic and they couldn't seem to figure out what was causing it, nor did the problem occur while they were trying to diagnose it. Since I got the car back from the mechanic it still stutters, and when it feels like the engine might die because of the stutters you can push down on the gas and it breaks out of the stuttering, at least temporarily. For the most part, the stuttering is less frequent at lower speeds than higher speeds, but still occurs at both. Any ideas what might be causing this?

Welcome to AF mjh1221.
Sounds like a fuel related problem, hav you tried changing the fuel filter? That might be whats up, but it also could be ignition related too. Like plugs and wires, how old are they?

Cant believe the mechanic couldnt figure out what was wrong, well maybe I can..
Hope this helps, Let me know what you find out or if you hav other concerns.

Thanks for your help, I've figured out the problem, as you said the spark plugs needed replacing, and the injectors were in need of some cleaning as well.

I'm glad you figured out the problem. I had a 89 Grand Prix (One of my favorite cars) and the the exact same problem. I was only 18 and didn't know very much at all. I took it to the dealer and they said it was the injectors. I allowed them to replace them. $600 for 3 injectors. Once I found out how easy it was I was steamed, I could have done it for half as much. Like I said I am glad you figured it out.

:thumbsup: