ok some background, 87 350 with tbi and auto trans. i put on an edelbrock tes exhaust system to replace mine which had rusted away. replaced o2 sensor with 3 wire heated version. now the darn truck coughs stumbles and stalls when its warmed up and in gear at idle, if i throw it in neutral or park it idles fine. only engine code is one that its running rich. whats the deal here? anyone experience this?