1999 Acura CL SLIPPING INTO NEUTRAL ONITS OWN

I HAD SOME AGING CV JOINTS THAT PROGRESSED INTO THE NORMAL PINGING AND BANGING WHEN TURNING. I GOT THE FUNDS TOGETHER AND GOT THEM REPAIRED AT A LOCAL PEPBOYS; FOR ABOUT 6 HOURS THINGS WERE FINE. TOWARD THE EVENING, WHILE CROSSING A BRIDGE, DRIVING ABOUT 50 MPH I NOTICED MY RPMs SHOOTING UP TO 4-6000 UNTIL I RELEASE THE GAS. I IMMEDIATELY TOOK IT BACK TO PEPBOYS. THEY WENT BACK THROUGH IT FOUND SOME LOOSE THING TIGHTENED IT UP AND BACK TO NORMAL. THE NEXT DAY WHILE OUT, THE SAME THING OCCURRED; I AGAIN RETURN, THIS TIME MANAGER PERSONALLY INSPECTS THE CAR; HE THEN SAYS IT IS THE TRANSMISSION GOING AND NOT THE WORK THEY DID. HAVING REPLACED A TRANS IN A PRIOR CAR I HELD OFF ON REPAIRING THIS ACURA. BUT I AM VERY CLOUDY IF IT IS THAT. THE TRANSMISSION DOES HAVE ALL THE ORIGINAL 115K MILES, AND THE AXLES AND THE ENGINE A NEW. I AM NOT SURE WHAT IS GOING ON AND RATHER BE PREPARED BEFORE GETTING BLINDSIDED. PLEASE HELP ME IF YOU CAN.