Transmission shifts 3-4-3-4-3-4 as I'm driving level pavement, 45-60 mph. Heard possible shift solenoid, torque converter lockup solenoid, or torque converter problem. Any thoughts? Looking for a good place to take car for checking every solenoid and switch ,. Maybe a tuner shop I'm in Cincinnati area. This is an extra car, so I have time to deal with it..Chevy charged me 150+ to diagnose and tell me" hydraulic issue". " 750.00 to remove and look at further.. BS. this is somewhat intermittent, say 80% if the time. Any thoughts?