GT Ran great, then timing appears Off

Here's one for the group.

Last Thursday I took my GT for a drive and it ran great. The place I needed to go was about 20 minutes away, so I thought it would be a great drive to burn out some carbon on the highway.

I was in my meeting for about an hour, maybe an hour and a half.

When I came out to start my GT, it wouldn't start. I had to jump start it and the timing seemed way off. The Tach was showing 7,000 to pegged rpm. A lot of back firing and coughing.

Specs:
My GT has a 1.9 bored to a 2.0 ltr. E.F.I. off a European 2.0 ltr. Crane electronic ignition.

Again, everything seemed great on the way down. Now it seems like it has slipped a cog on the timing chain or the ignition is firing way off.

Any help would be great.

Chris