2004 F150 Lariat 5.4 4WD - I think I've got the 4R75W

I had suffered the same O/D clip problem as almost everyone else. I found a laundry list of broken parts, which were replaced with genuine Ford parts.

• Broken overdrive servo ring clip (big clip)
• Bent overdrive servo
• Broken overdrive servo stiffener plate
• Hole in valve body seperator plate, with ring clip fragment embedded
• Broken 2-3 accumulator spring
• Bent/damaged 2-3 accumulator piston
• Bent 2-3 accumulator retainer plate

After the repair, it drove fine for about 1-2 weeks, and now on the way home from work, I feel like the truck drops out of gear every time I let off the gas.

From park, If I shift to Reverse, the transmission engages as I feel it should, and applies power immediately.
From park, If I shift to D/2/1, any forward gear makes no difference. I still feel like the truck is in neutral when I let my foot off the brake. The truck will only move if I rev the gas, and even then, it doesn't feel like the transmission engages completely. It feels like a very slow apply. Once I take my foot off the gas, I have to rev to get it engaged again.

Turning O/D off does not change this behaviour.

Should I expect my forward drum to be burnt?
Is there something in the valve body that could be causing this?