Sounds like your speed sensor is testing fine. Plug it back in. I have been checking into this problem further and it seems like it is a common one with the VR6 engine. They seem to have a carbon fouling problem that can cause this issue. It seems the best way to deal with this is as follows:
You need to remove the spark plugs, clean them with a wire brush if they're fairly new or replace them with new NGK plugs if they aren't. Pull the fuel pump fuse (third from the bottom on the left most verticle row of fuses) and crank the motor for about 10 - 20 seconds with the plugs removed. Then you need to put the spark plugs back in and crank the motor over for another 10 - 20 seconds. Now put the fuel pump fuse back in, hook jumper cables or a battery charger to the car, hold your foot to the floor on the accelerator pedal, and crank it for about a minute or until it starts.
It will start to kick over at one point but will stutter and not be started, don't stop cranking until the rpm starts revving up or you've been cranking for a minute already.
Wait 5 minutes and try again if you crank for a minute and it doesn't start. It will smoke like crazy when it gets going DO NOT turn the car off until it gets up to operating temperaute.
Another suggestion is to remove the air intake boot to the intake and use starter fluid to get the car started. Then replace the intake boot and start the car on it's own holding the pedal down to keep it going until it clears the carbon out of the system. Always run it until it reaches operating temperature (radiator fan comes on or needle points to around 190 deg F) after doing these things so that it will burn off whatever is causing this problem.
If this helps let me know. Click Accept if you get her running this way.