I went from a 93' style opti to the 95+....I am having ignition problems I beleive...

I have an MSD 6AL BTM on the car.....with the MSD hooked up, it runs fine, but when I go back to the stock wiring harness, the RPM's are fine at Idle, but when I rev it up, the RPM's go down (on the factory gauges)

The car pops out the exhaust like the timing is off or somthing after it warms up. I was going to go back to my 93' opti to see if it would help, but the timing gear doesn't have the splines for the opti shaft, and the timing covers are different.

I also used the 95' harness for the opti....anything special I have to do or should have done to make it work properly?? I have also replaced ignition modules...didn't make any difference.

Any help is VERY appreciated....