Go to tcc lockup parameters in xfi
check to see where your "min%TPS for TCC" is set at, if it is to high a value it will unlock when you ease off the pedal past a "X" value. You might bring the number down a little to help.
To keep it locked under acceleration, raise the number in "max%TPS for TCC" to keep it locked under heavier throttle.
I'm by no means an XFI guru but had the same situation on mine when I had a lock-up converter, constant lock/un-lock even with the cruise on. Changing those parameters fixed mine.
HTH
Check out chapter 19 in the operation manual to get a little more insight about TCC parameters:
The ECU can control a torque converter clutch (TCC) in an automatic transmission. The TCC output
(ECU pin B6) is switched to ground when the ECU determines the TCC should be locked. The ECU will
lock the TCC when %TPS and vehicle speed meet user-defined thresholds. To get vehicle mile per hour,
your vehicle must be equipped with a vehicle speed sensor (VSS). That VSS will need to be calibrated to
your ECU using the Rate Sensor Calibration found below in this section.
19.2 Min %TPS for TCC Lock
This parameter sets the minimum %TPS required for TCC lockup. It is used to prevent TCC
lockup during closed throttle coast down. By unlocking the TCC, the engine is allowed to rev
lower to conserve fuel. This would normally be set between the “TPS %” readings at idle and
cruise. It needs to be set lower than the “Max %TPS for TCC Lock” setting.
19.3 Max %TPS for TCC Lock
This parameter sets the maximum allowed %TPS for TCC lockup. It is used to prevent TCC
lockup during heavy acceleration. An unlocked TCC will prevent wear and allow the benefits
of torque multiplication to be realized. This would normally be set between the “TPS %”
readings at cruise and at WOT. It needs to be set higher than the “Min %TPS for TCC Lock”
setting.
19.4 Min. MPH for TCC Lock
This parameter sets the minimum vehicle speed required for TCC lockup. This setting is used
to prevent TCC lockup at low speeds, which could lead to stalling.
