I recently purchased a 1993 dodge caravan. It has stalled several times when it goes uphill or over bumps in the road. I took it to firestone and I purchased a diagnostic for 100 hundred dollars. The diagnostic stated that I must replace the catalytic converter and it needs a fuel system cleaning. I did both items listed, the car still stalled. I called firestone back and they told me that the diagnostics was just for problems right then as I brought it in. It was my understanding that the diagnostics should determine everything wrong with the car. It was manually diagnostic done. What else could be wrong with this car.