Ok, I need some SERIOUS help here guys. I went out side this morning before work to worm up my car. after it ran for a few the check engine light came on (UH OH)

i thought WTF and checked around a bit but evenually had to head off to work. As i was driving down the road (light still on mind you) my Tachometer started to fluctuate. as in it moved up and down rapidly and randomly.ALL OVER THE PLACE!!

but it didn't effect the engine itself (drove ok). I was worried about it all day at work....finally left wrok and it did it again!! AHHH, but this time it DID effect the engine. The engine basically mimicked the tach's movements (barely made it home). Also while i was trying to make it home, the check engine light (which was still on) started to blink for a bit (maybe 6-8 blips) then went constant again. PLEASE, if anyone has ANY idea of what this might be, let me know. I can't afford to lose my baby. I would GREATLY apprieciate it.
~Chris