Mitsubishi Repair: car jerking, advance auto parts, spark plug wire

Question
1998 3000GT, v6, automatic, when driving car if the overdrive in on the car will jerk and stall you just can't drive it with it on. with the overdrive button off the car usually drives fine but sometimes still acts up by jerking and it seems like downshifting. To explain in another way.  You know how a chev when you hit 100 the engine like cuts off and then when you get down to a lower speed the engine cuts back on and how that feels that is kinda what the 3000gt is doing but it jerks worse and it does it at various lower speeds.  The car started making a loud noise.  we tore down to the flywheel which was loose we tighted it up and noise is gone. but still have same problem with the jerking what could be causing it.  could a possible cut in a spark plug wire cause this? Or is there a sensor in the transmission that could have gone bad.  I have taken the car to a transmission shop. They said they can't find what is wrong.  Transmission shifts fine for them when they hook it up to computer. They said the tranmission is not giving them any errors.  maybe its a sensor but they didn't know where the sensor is on the car. Or could the selinoid be bad or the converter? I did take it to an advance auto parts since the check engine light was on and they told me the error code was P1750 - Manufacturer Control. Transmission.

Answer
Paula,
The Mitsubishi specific description of code P1750 is the Solenoid Assembly.  The solenoid assembly is responsable for shifting your car into different gears.  If your transmission shop is not familiar with your particular car, I would recommend having the dealership service your transmission.  Misdiagnosis at a cheaper transmission shop can cost you more in the long run than simply having the dealership fix it correctly the first time.  Take it into them and see what they say.  It's possible it's just a loose harness or electrical connection.
Good luck!