1998 4r70w trani acted like it went into neutral when I turned a corner. Fluid level was full. From ther it progressively got worse (about 3 days) to get it to go forward I had to increase the rpm more and more. it has about 98K miles. Changed the fluid and filter (twice) second time I drained the TC. I used a suction gun to refill the TC till the fluid started to come out of the valve body (didn't want a dry start). It had minimal deposits on the magnet the first filter change basicly none the second change. I have heard the seal/O-ring on the forward piston and electrical and valve body. Any one have this issue that found a firm reason for it???
Also for those concerned about the little yellow plug with a O-ring I had one in my pan also so it was the first filter change on my trani.