1997 Gmc Jimmy 4.3l Problems?

The coil went bad in it and replaced it.It ran fine for about a week and started missing. The rpm gauge started jumping sometimes and and random times the engine would stall but the car start right back up. I drove 150 miles away and back home and it only missed a little. Went out the next day and it broke down. I towed it to the mechanic and he said the new coil went bad so he replaced it. It worked fine for about a week again and its missing again. Need to know how to fix it before it breaks down again.IDK if this has anything to do with it but the dashboard blowers for the AC are not blowing at all and its a new AC.

This is all we have replaced since January.

Distributor cap and rotor button
Fuel Pump and fuel filter
ignition control module
ignition coil TWICE
ignition switch

Suggestion:

The pickup coil in the distrubitor .has all the symptoms .