This is not an easy question to answer, is the car running right yet? The high voltages could cause damage to the duraspark ignition module, the coil, the pickup in the distributor, various electric emissions components.
Do you know anything about working on cars yourself? Have you looked at your spark plugs. Sometimes you can pinpoint your problem by how they look. High ignition voltages could have ruined the electrodes.
We would need to know what all the dealership did to your car while "trying to fix it".
Also, is the egr valve still on the car, sometimes they stick from age and deposits, and will cause a car to do strange things. Without being able to look at your car and hear what it is doing, it is very hard to answer your question.
If you know what the egr valve is and where it is at, if you have a hand operated vacuum pump, hook it up to the egr valve vacuum fitting and start pumping and see if it moves, there is usually only about 14 lbs of vacuum, so if it takes more than that to move it it is probably defective, if it doesnt move at all, it might be stuck open, then try pushing it closed.
As far as the choke goes, if it isnt closing right, it wont run right until it warms up. It it isn't opening right it will start up ok, but not run right trying to drive it.
You can start the car, get it warmed up to operating temp, and wire the choke in its open position. Go for a short drive if it wont run this way, or has no power, the problem lies elsewhere.
What kind of carburator is it. Different carbs have different problems associated with them. I cant help you much more than this without furthur info.