tack going crazy

hay all.
I have a 95 n/t that is giving me some truble.
somtimes when I am accelerating my car will surge and I think that it is misfireing, when this happens my tack (rpm gauge) will go crazy.
my dad seems to think that it is a short somwhere, my friend said that it might be a cam sensor going out.
any input would be great.

oh and when this happens my check engine light comes on.
I have changed my wires and plugs
?????
thanks
ben

I've heard of crank sensors causing this. I believe the tach gets it's signal directly from the crank sensor..If i remember right..Been a bit since i tore into a mistubishi.

EDIT: My book says the engine will continue to run if the cam sensor goes out. So you can rule it out.