my rpm needle doesn't move at all. Is that a serious concern?

It might be a speed sensor, You should have this checked because not only does it operate the signal for the speedometer, It also has information that the computer needs to operate the car. We would be happy to assist you. give us a call Action Auto Services 224-801-6094

Hello, Yes, it could be. Your engine uses the crank position sensor to monitor engine speed, and failure of the sensor can cause the vehicle to run poorly, or stall. The signal to and from the crankshaft position sensor needs to be tested. If the sensor is getting good reference voltage, then signal voltage should be normal as well.