1998 Malibu

I have a 1998 Malibu. I am having an issue with something that I am tired of throwing money at and getting no results.
This does not happen all the time, but often enough. When I am driving the Tach goes crazy and then will stop working all together. While this is happening the car seems to threaten a stall. It will spudder, and sometimes if I am not going fast enough it will stall. I have replaced both O2 sensors. It fixes the problem for a little bit (meaning a day or so) and then it goes right back to the same thing. I do not know what to do and what the problem is. Someone please help!!!

Sounds like an electrical fault ... possible a harness ground connector somewhere.

I noticed today that when the tach stops working altogether the car runs like normal. Would that still be an electrical issue? Is that an expensive fix? Because of what happens when the tach stops working I was beginning to think that it was electrical. The car will stall out if I am not going fast enough (above 30 mph). 

Check all your grounds for your ECM, probably a corroided ground.