97 318i problems

I got a 97 318i with 80,000 miles on it. I've got a few technical problems i need some definite help with.
-The whole entire console flashes on and off, the air conditioning comes on and off, and so does the heater.
-The car doesn't want to start after its been sitting for 3 days.
-The ignition switch has to be twisted a full 180 degrees before the car can start.
-check engine light is on, and I've changed the plugs, and the air filter

test the ign switch,common problem.