97 Caravan misses, gauge problems

Haven't seen one just like this on this forum, so here goes. We have a 97 GC 3.3L. July 1st the wife parked in a lot, but when she came out it would not start. Turned over fine but no start. GFinally had it towed to the only shop opened over the holiday weekend. they replaced to cam sensor and it seemed fine for a couple of days. Then it started to skip and miss. Took it back and they replaced the coil pack. No good. Now it missed and began a new trick, bucking. Twice we took it to the dealer. First time they replaced the plugs and wires. next day the crank sensor. They said they couldn't be sure because there were no codes set. Swapped out the computer for one from an identical make, model, & engine, No difference. Reinstalled the original. The next week it bucked so hard it snapped a half shaft. Our regular mechanic kept it for several days. It missed, and stalled for him too. He said he got a code that indicated a problem with primary circuit #3 that affected #3 & #6. He checked the wiring but couldn't track it down. Did a fuel pressure test and it held 50lbs right up to the point the engine stalled. Throttle body cleaned and EGR replaced as it was leaking TB cleaner. When it stalls the rpm's raise to 1200, drop to 400, back to 11-1200 and up and down till it stalls. Once I even noticed that when I started it back up, the tach and spedo both moved up the same together. After declaring the van haunted (LOL) I finally have it at a fourth shop run by a former chrysler tech. The tech working on it told me yesterday that he has seen the spedo at 120 in park. Talked to him yesterday. He believes he straightened the bucking out. Now it only does the gauge thing and misses until it gets warmed up to operating temp.
If anyone has had the same problem please let me know what was done to fix it, short of a gallon of gas and a match. Thanks Jay

Short Update: Cars been in the shop for 3 weeks now. Stars right up but misses and hesitates until it comes up to operating temp. After that the tech says it runs great. He showed me a connector that hooks two bundles of wires together above the top of the motor. Says he gets dimming of a test light when it hesitates on two of the wires. Any Ideas? Thanks

Which wires and where do they go? The mechanic should have been able to nail down the cause if he had that starring him in the face. Try another mechanic with some electrical experience.

A PO353 fail code indicates a failure in the #3 coil circuit. You said he said the wiring was good but, were the primary and secondary resistance readings across that coil within limits? Primary should be .45 to .65 ohms. Secondary should be 7,000 to 15,800 ohms. There could be a heat related coil failure until the engine "warms up".

When you say, "swapped out the computer" you must mean the PCM.

The Vehicle Speed Sensor (VSS) appears to be the signal source for the speedo. It's signal also is a conditioning signal for idle air control motor which inturn is used for fuel control and transmission shifting.

I've heard aftermarket sensors can give you headaches. Are they installing Chrysler parts?