I have been working a couple of days on a 1991 Mazda MPV 4x4 V6 3.0L. The van starts and runs fine; however, whenever there is a large vacuum change or the vacuum at the intake manifold is high (at
3000RPM) the distributor stops putting out sparks to the plugs(no spark). I have changed the spark plugs, the spark plug wires, the distributor cap, the rotor, and the whole distributor for a new unit; the symptom is still the same. Is there anything that would cause the electronic iginiton to cut off the signal to the distributor (no spark hence)? I am lost on this one, I thought it could've been the TPS, but I have test it and it seems fine. Moreover, I unplugged the TPS and try running the van with the exact same results. I have also changed the Oxygen Sensor with a new OEM unit (to no avail may I add). I also thought it could've been the crank angle position sensor, but it turns out in the MPV (please do correct me if I'm wrong) the sensor is inside the distributor. Anyone out there have any idea what could be wrong? Is it the ECM? Thank you in advance for any help,- JR