Stalling/hesitating

2003 dodge caravan 3.3 automatic 151 000km
sometimes it does not start right away, it will hesitate while driving, or it will stall when we take off from a stop sign or a red light.
the engine light does not come on and the computer scan has come up negative several times.
we did a leak test on the fuel pump, have replaced the fuel filter, plug wires, and the pcm.
Replacing the pcm seem to have done it for a while but the same problems are occuring again.
There doesn't seem to be a mechanic in our city that has an answer for us.