Sputtering 9920 and hot caps

[giftacrylic]

Converted a Jammin Truggy to brushless a few weeks ago and ran it on 12 cells without any problems. Yesterday, dropped the gearing down a tooth and ran it on 14 cells. Ran great for 5 minutes, then most of my power subsided. Thought my batts were drained so I recharged and tried again. This time, it sputtered violently then took off. The 9920 was not hot but the caps were very hot but not bulging. Switched batts, reprogrammed controller and checked wires. What else can cause this problem?