My ride is a 93 Sunbird Ford 302 v8 502APRJVB with the Cobra and Holley 2bbl, and Prestolite ignition. I have been chasing an intermittent rough idle / low speed stumble for at least a year. Rebuilt carb, and put in new plugs, wires, cap. rotor, and fuel pump/fuel line, checked timing, no difference. The boat will idle @ 600 rpm for a minute or two, then stumble a bit, then recover, then stumble again. Over 1000 rpm the engine rides smooth and powerful. Yesterday after a 20 minute ride with no issues at 30 mph, as I pulled into my slip the engine started to sputter again. In messing around with it while it was sputtering I noticed that if I disconnected the plug to the shift assist module (the one mounted to the left side riser) the idle would smooth out, but then I could not get the drive out of gear. Since the function of the shift assist module is to stumble the engine, mine would seem to be working, but possibly engaging and not releasing when it should, which leads me to think my shift cable is going bad. My question, what should I do next as far as diagnosing? Can the module fail and come on when it shouldn't, or is it time for a new shift cable?
