I have a 99 dodge durango and the motor keeps surging / reving when started up is this a simple oxy. sensor?

Sounds like a Throttle Position Sensor. If the "Check Engine" lite is on, you can have some one check for fault codes with a scan tool. If the "Check Engine" lite is NOT on, there will be no fault codes. Then the Throttle Position Sensor will need to be tested with a Lab Scope for voltage spikes and/or voltage drop-outs. This sensor tells the engine computer the angle of the throttle blade, and if it is sending erratic signals to the computer, it will move the Idle Speed Motor in and out, causing the surge and revving. Chrysler did have some problems with these sensors, so it's a good bet that's the problem. HTH! Good Luck!!

Don't put your foot on the floor when starting! LOL

Seriously, though, it sounds like an idle sensor or something has gone away on you, take it in for a tune-up.

Bring it to Autozone and have them check the engine codes for you, it is free and they should be able to tell you whats wrong.