My son has a MX-3 that stalls whenever it's put in drive, it runs fine in park or reverse. He said that it started with a hesitation when he attempted to take off from a dead stop and has gotten to the point now that it dies. I've looked for vacuum leaks, replaced the fuel filter and fuel pump plus the fuel pressure regulator. I don't know what else could cause the problem since it sounds to me to be fuel related. Any suggestions?

 

The Mazda gear select system sucks bigtime. It's a freakin' bicycle brake cable type of arrangement linking the console lever to the transmission via a pretty snaky routing. Over time the inner core wears the jacket at the bends and the indexing between the console and the selector switch on the transmission itself gets far enough out of whack that gear selection is affected. The linkage is adjustable though, so the first thing to do is check that out. Beyond that, it's possible the problem lies in the speed select switch itself, the solenoids, or the solenoid driver electrics.
Before getting in too deep though, check the transmission fluid and level. If the fluid is pink or light tan and doesn't have an acrid smell, that's fine; otherwise consider a major transmission overhaul/ replacement. Spending money of a tranmission control overhaul when it's evident the transmission itself has been abused or neglected is like carrying your beer home in a wet paper bag.