2001 Mazda Millenia Stalling/Surging and Check Engine Light

My Mazda Millenia has been intermittently stalling at stoplights and stop signs that I am going 5 mph or less. The transmission 'hold' light on the cluster has also been coming on every once and a while when driving. I have these codes when I use my scan tool: P0750, P0755, P0760 and P1743 which are all related to the Shift Solenoids. Also the engine surges with 1000 rpm swings as if you were taking your foot of the accelerator abruptly and then pressing it down again.
I've had the car to my dealer, and a reputable independent transmission shop. Both of them could not find the problem, and after extensive tests the y both determined that this is not a transmission issue in spite of the codes.

The strange thing with this problem is that this car will run normally for days and then the above symptoms reappear and then go away. There is no relation to weather/rain or any other factor that I can identify that explains the random nature of this issue.

I've owned the car since it was new, all basic maint. Items are goo (plugs/filters etc.)

In addition, I've replaced the distributor, crank position sensor and ECM. I'm quickly approaching $2000.00 with parts and the trips to the repair shops above.
I would appreciate any help that you can give me on these issues Thank You!