2000 Volvo V70 starts, but then shuts off

Please help me! I have been having this problem for a while. I did have the key radio transmitter whatchawhosit replaced already. My car still while turn over, start and then shut off. Yesterday, this happened and I continued to crank the engine to see if it would go, and the whirring started to sound like it was dying. We have replaced the battery today. I started the car this evening, it died again. I banged on the steering column, tried again, it turned over, I gave it gas and now it revs really high and comes down to idle (obviously it stayed at the high revving longer than normal when you hit the gas). What now?