1992 Toyota Previa LE AWD van rare model Runs but has intermitent wiring problem

This van was running well until recently. I took it to my local Toyota dealer and they installed a new battery. It runs and drives for anywhere from a couple of minutes to 15 minutes and then stops. The dealer said it was a wiring problem and could not give me a quote for fixing it as they would have to do "exploratory" work. I can't afford this now so decided to sell. Ideal for a mechanic or if you know someone who is good with electrical problems. The only two other issues, and ones that can be easily remedied are: 1. the sliding side door has come loose from the track and needs reattachment; 2. the ignition key is stuck in the ignition and would need to be taken to a lock shop to have it removed (I didn't want to force it and take a chance on it breaking off in the lock). Van has 205, 575 miles and is located in Novato, California. You will have to have it towed as there is no predicting how long it will run before stalling again. It will start and run so you can tell the engine & transmission are fine. $500.00 deposit by Paypal within 24 hours of purchase and balance when you pick it up. I can have it towed to anywhere you like at your expense.