Ok, I just got home from a 16 hr shift at work and all of a sudden my tach starts bouncing around while im driving. When i give it gas it bounces, when i idle it bounces, and then a check engine light comes on. Any help would be very appreciated

 

what were the codes from the check engine light? I had this happen with a 1985 Z28 and it was from the brake boost valve being offset a little. Bleeding the brakes took care of the problem. Don't know if the same will apply here.

The Trickster!!!!!!!!!!!!

 

Check to make sure all the plug wire boots are tight. One of mine popped loose and started doing that.

 

I just checked the codes and it came up a code 42. I have no idea how to fix that or what it involves, so suggestions are welcome.

 

How's the alternator and charging voltage?
Sometimes a failing alternator will cause the tach to jump.

 

Code 42 is for the Electronic Spark Timing system. If the tach is jumping along with the code and the misfire, the problem is likely in the distributor. Remove the cap and inspect all wiring at the distributor. Check for water, buildup, damage etc inside the distributor, paying particular attention to the wiring and HEI module. Check inside the cap for arcing or carbon trails, anything that looks unusual.