Help!!! I Think It's Blown!!!

I own one 91' but it's sitting in my garage, not operable at this time. I have next week off and I have time to fix it. They last time it worked was when driving at average speed 45mph on a straightaway, after driving for about 4-5 min. the engine just shuts off, meaning the rpm's went to 0 speed decreased until I got to a halt. My problem is that the engine (30VGDE) will not start. What happens is the crank turns but very, very slow. The starter engages. I haven't check the error codes yet but will. I will also remove the timing belt cover, in doing so I will check if the timing belt skips a groove or so. Anyone have any suggestions, maybe bent valves, melted pistons per say. Any help would be appreciated.