radio interference
I'll just share what I encountered. I run the 4PKS with the 603FS RX and Savox servos, had some glitching issues too. The Savox servo wires are really long so I stuffed them along with the power wire running from RX pack, into the RX box. With all those wires sitting on top of RX caused some interference. I shortened all the wires running into RX box and problem went away. Also check to see if your RX pack has plenty of juice. Low voltage on the pack can also seem like your systems glitching. This is just my experience and hope it helps any.