Hi,
I once had a similar problem with my 6 when someone put my dist cap on wrong and tried to start it. It took me forever to figure out, but the tell all is to hold the rotor and try to turn the gear on the bottom of the dist. Basically what had happened to mine was the rotor jammed and the center screw loosened and rounded the optical wheel. The thing would readjust itself ever so often and kill the timing. Another thing you might check the maf and make sure the connector is tight.
Hope this helps,
Phil