I HAVE A 1997 DODGE RAM 1500 4X4 and it feels like the hand brake is on but not?

THE HAND BREAK IS NOT ON IT JUST FEELS VERY HEAVY WHEN ACCELERATING TO FIRST GEAR THE RPMS GO HIGH THEN NO PROBLEMS AFTER FIRST GEAR MY HUBBY CHANGED OUT THE WIRES SPARK PLUGS CAP AND ROTOR AND PCV VALVE AND CHANGED THE OIL ON THE MOTOR AND ..WE R NOT HAVING TROUBLE WITH THE TRANSMISSION WOULD THE O2 SENSOR HAVE ANYTHING TO DO WITH IT ? IT JUST STARTED ACTING UP ONE MORNING AND NOW WE DONT KNOW WHERE TO TAKE IT TO OR WHO CAN HELP ? ANY SUGGESTIONS WOULD B GREAT.THANK YOU