Major Electrical Issues...Help!!!

[BDSDC]

After motor change to JDM motor I was able to drive approx 20 miles. (Intake Manifold changed over with emissions and wiring from original motor.) Car began running ruff, not shifting properly, and speedometer began bouncing around. Now, when the car is started, speedometer doesn't work for a while and then goes up to 40 mph in park and odometer runs also in park. Since, have changed speed sensor, TCU, ECU and Mass Air Flow Sensor with no help. According to manual speed sensor wire should be 0-5 mv? and it is 12-15 mv?
Mechanic has no clue. Any help would be greatly appreciated. Also, could the regulator in the alternator be bad and cause this? New rebuilt alternator changed approx. 1 year ago.

Finding that mechanics want nothing to do with this car.