After a weekend of diagnostics I have found the problem. Yet another weird bolt coming loose. The bolt that goes into the end of the crankshaft has come loose and caused the lower timing belt sprocket to stop turning under load - that's why the valvetrain turned when I cranked the starter. Now all I have to do is get the bottom half of the engine in time with the top half. I've done a timing belt replacement so I already know how to find TDC on the top and bottom and get them to align. By the way, the door handle problem is exactly the same one I had with the driver's rear door last year. The pull handle broke where it goes into the main handle body. I got a new one at the junkyard and I'll put it on as soon as I can get it to run again.