the erratic rpm tach problem...

cwin13

So I have the erratic rpm tach problem where the rpms go crazy at 3k and up. Last year when it did this I changed the cap, rotor and ignitor and it was fine til about 2 weeks ago and it started doing it again. The car has stalled a couple times but starts back up and is fine for a while. Just wondering if anyone has a permanent fix besides just replacing the ignitor a thousand times lol the car is a 91 wagon rt4wd all stock everything with 94k miles. Thanks ahead of time