Tom Hoppes

I covered the vent on mine over the cold months mostly to keep the dust out of my soft cab.  Didn't notice any temp problems.

I must be lucky since I've had zero problems with my Buck 400 in 700+ miles. 
As mentioned above the ignition switch sounds bad.  Mine shifts hard or grinds if the motor is on high idle, I just give it a second or two to slow down then no problem.

Richard, I'm betting you have the wrong ecu in your machine.  Call Massimo and  they will send you the right one.  Where the law limits slow moving vehicles to 25 mph is where the ecu you have is used.

The filter is under those screws, I replaced the screws with 6 metal clipboard style clips to make it easier to get too.