is it cause the TC locks as soon as it shifts when you're cruising around 1.8k rpms
1998 Grand Prix GTP Daytona - CAI, XP Cam, Iceman tune, Speed Daddy Headers, 3.2 in pulley, Ported blower, Al 103's, 3in Catless DP, Transgo "shift kit", No resonator to Magnaflow Mufflers. 93K Miles