RPMS jumping around or Low! Speedometer jumping! Car stalling!

Hey guys I have a 1999 Pontiac Grand Prix V6 3.8 L supercharged! I recently changed my power steering pump & hose there was a super bad leak . Of course I fix that and then my car starts acting crazy . Another check engine light came on saying it was the O2 sensor(had to unplug this to get the power steering hose back in ) , however I do not believe the sensor is causing my car to stall out , my speedometer to not work or read way to fast ! Also my rpms seem to be fine when the car is just started but after running for a while is when everything starts to trip . That’s when I start to accelerate it lacks and will not go faster then about 40 miles I’m assuming since my speedometer isn’t working ! When I let off the gas the rpms DROP super fast and will cause the car to stall out if I don’t drop it in neutral to keep the rpms from going under . Any ideas !!! Supercharged Pontiac Grand Prix , stalling , sputtering not accelerating when hot?? HELP !