Tuning seems to be going well but I noticed the other day while cruising about 70-75 down highway that as soon as I hit about 2500 rpm tack starts lunging between about 2400 and 2700 rpm, like its going in and out of lock up. If I slow down below 70 and 2400, it stops. Could this be a ECM/program issue? Truck never did this prior to new motor.