The tach jumping at key on sounds like either the battery is low or its not getting enough current through a bad connection. I forgot have you checked the condition of the battery and the connections?

 

it didn't jump for no reason, when the A.I.R pump jumped the tach jumped with it. It didn't do it ever again.


the battery is 6 months old and connections are good.

 

The age of the battery means nothing with regard to charge. If you've been cranking it a lot but not letting it run for long periods of time, it could be low on charge. If you want to test it, check the voltage across the battery while someone cranks it. It should not drop below 11 volts.

As far as the hunt for your problem is concerned. It seems that the opti might be the culprit. So perhaps one more test before you pull it off. Put the car up on ramps at the front wheels. When it's completely cold, start it up to see if runs but only for a few moments and shut it down. Get the hair dryer and warm up the opti as best you can until it too warm to touch but try not warm up anything else. Now test it for the problem again but not too long incase you have to warm the opti some more.

What do you think?

 

I think OPTI or ECU. but im leaning more toward the opti.


2 of my friends have LT1's so i'll swap out an ECU if i can get a hold of one