I was driving my 93 Integra today and i noticed that my stock tach jumps. I have a safcII and the rpm reading on it stays the same(as i can see). It jumps from about 2000 to about 5000 but only when i am bogging a little or in second gear at like 2500 then accleerate. It doesnt do it in neutral or at idle. I was thinking maybe a loose connection?

Any help would be greatly appreciated.