i just put a 3 inch catback exhaust on my 95 sohc dodge neon plus a new catalytic converter and o.2 senor but now my car is only hitting 4000 rpm's and when it warms up it hits around 2000 rpm's why would it be doing this?

 

Did you change O2 with a wideband?Change it back to stock.3in exhaust robs the backpressure needed for this little motor too run correct,but sound OK.Start by changing the O2 and pull the pos from the battery to clear the PCM to re-learn the new O2,takes about 5min.Just a thought...........