I had amoajor problem with glitching that took me months to work out. what i ended up doing was :
1, adding extra little capacitors (3) and not relying on the ones that come pre installed on most motors. ( + to can, uswe the hood screws - to can, and + to- can. they only need to be about small.)
2, keeping a close eye on the comm diameter, and if it gets down to about 1/2 its original diameter, REPLACE IT
3, after every run i now take as fine file to the leading edge of both + and - brushes.
4 re wired the car with new 14g deans wire. (not sure if this actually helped, but my car needed it anyway.!!
5, shortenbed the wires from me reciever to servo, and rec. to speedy.
6, try differeent positions to mount the reciever, and if possible the speedy
7, i tried some ferrite magnets over the motor, &/or the battery wires. (didnt help me, but i know some people who haved benifited by this, try the Yokomo noise reduction kit)
8, try somone elses reciever,
9, if none of these work, well then i dunno!! have a beer or 3 and worry about it later?!
see how you go