88 V10 Suburban problems

[Sgt_solo]

I have an 88 V10 Sub, Silverado, with the 350 TBI, 700r4 trans. I've already replaced the disributor, rotor, cap, wire, plugs, ECM, fuel pump, fuel relay, starter, battery, cables, radiator, water pump, thermostat. When I drive at highway speeds and slow down it stalls out, then will stall every time I slow down. I've heard of the 700 having a TCC problem, how do I check that? Is there anything else I can check? Pictures help. Thanks.