Really digging for mistakes now...
Have you tried taking your spektrum module out of your transmitter and cleaning the pins on the transmitter?
Remembering a friends mistake with his 3vcs have you maybe got one of the channels set to one of the toggle switches on the transmitter that is maybe in the wrong position? A friend who shall remain nameless had something set to one of the switches at the top of the transmitter and come the start of the final got a really great start full speed into the wall
If you want to try the capacitor in the receiver let me know at the race.