Please see the most recent updates in the "Where did the .com name go?" thread. Posts number 16 and 17.
It turns out I had to comment out the default flight from fsx.cfg and FSX defaulted to Friday Harbour, microlight etc. Loading the Bronco and changing airfield etc gave me a running, starting (if necessary) Bronco after that. Things had been so bad the default King Air 350 and PC-7 weren't behaving either when I tried them. 
Glad you got it running Tom. Only problem I have with either of those two is trying to get the OV-1 to stop creeping while in idle and then to slow down on landing, lol.Thanks all for the suggestions, but none worked.It turns out I had to comment out the default flight from fsx.cfg and FSX defaulted to Friday Harbour, microlight etc. Loading the Bronco and changing airfield etc gave me a running, starting (if necessary) Bronco after that. Things had been so bad the default King Air 350 and PC-7 weren't behaving either when I tried them.
Funny enough, the OV-1 never gave any problem and it has twin turboprops too...