This problem is caused by your crank position sensor (cpk). It's located behind the rear of the valve cover on the bellhousing for the tranny. You can buy them at a parts store or a dealer. Its a small black cube with a wire that leads to a harness on your intake manifold. It's a real P.O.S. to change, mine was doing the same thing and it finally quit leaving me stranded forcing me to articulate myself to replace it.
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