I have a Cat P6000, customer changed fuel vaporizer themselves. code E21 is flashing on dash and dash lights flash as well. I have replaced MAF sensor, engine sensor/injector (threaded 2 wire solenoid) on carb and engine now runs smooth but when accelerator is pressed, it dies out. i also tried the pedal dance about 20 times and then replaced throttle position sensor and still no luck clearing codes or getting lift to run proper when pressing throttle pedal. I inspected every wire and connector possible and found no breaks whatsoever. When I press throttle and spray brake cleaner into airbag, lift runs great until it dissipates. What could I possibly be missing?