Wondering if there might be a connection. My engine began to stumble under accelleration about the same time that my tach needle started bouncing. Does the tach filter cause the bounce? Could it affect the engine miss?

I would put my money on a bad ignition module.

That would cause your miss and that would explain the tach bounce at the same time.
Tach bounce when your engine is running fine with no miss is usually the tach filter only.

Change the module... mine did that for about a year... I got used to it and then the car left me stranded with a new module on my TV at home... 27 miles away. Replaced the module and the car runs better than it did before...

Change the module... if you want you could replaced the connectors on the coil(grey and black) with ones from the Fiero Store... they do tend to get stressed over the years... its a poorly designed connector as far as wire stress is concerned and they can get intermittant.

I third the motion on changing your ignition module! Better carry a spare just in case. I can count on both hands the times i had an ignition module crap out on me in the middle of B.F.E. .

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"but when equipped with NOS, sometimes I feel invincible..."
"but when I race from a roll it's hard to hit 2nd"