[mcguyver]

Try a larger capacity battery. Seriously. I have the same gun with similar upgrades and it has a hard time running those upgrades with the PEQ 9.6v 1700mah battery ICS supplies.

You also have to make sure the shiiming is top notch. I've shimmed more guns than I can count and it takes me an hour to do an ICS M4 lower, but 10 min. for a Marui ver.II. You have to shim the anti-reversal latch as well and you may want to recheck the sector gear shimming to ensure it's properly contacting the semi-auto cut-off (or sway bar as ICS calls it). This will render all your other shimming as useless and you'll have to start again.

The reason you have to push the forward assist is because you are sometimes starting the fire cycle with the piston already in the middle of a fire cycle. This is causing your motor to be under a much heavier start-up load than when the piston is fully forward in the cylinder. The ICS battery (if that's the one you're using) is incapable of delivering the inrush current to the motor when you increase the load by using a heavier spring. Changing motors makes no difference either as it's not a motor problem, but rather a current delivery problem. When you press the forward assist, you return the piston to the start of the fire cycle and decrease the intial start up load on your motor.

And as far as timing goes, there is no such thing. The first full auto burst you fire automatically sets the timing correctly. Semi auto uses the sway bar to set it's own timing and this is not adjustable in any way. It's the biggest myth in airsoft.