my tach is jumping around...without the RPMS to make it jump...any ideas???

 

or not

 

check the ICM

 

Does the car bog when it jumps or does it seam completly fine when it jumps? Any cels?

 

ignitor maybe?

 

my tach did the same thing.
if you searched you would see plenty of topics that cover this but..
i fixed mine by taking the distributor cap off and tighten the wires that go to the ignitor, use a pair of needle nose pliers and make sure the connections are tight, if that doesnt fix it, its probaly the ignitor itself

 

It could be the igniter it could be the whole dizzy. I have an igniter for sell if you need one, check sig. I bought it from len.