Hi I am new to this site and hoping that i could get some tips or advice to what is going on with my eclipse.

I have a 2000 Mitsubishi Eclipse 2.4L Automatic (GS) when i had found this car it had been sitting in a garage parked for 5 years and only had 92,000 miles and i bought it for $800... but when i got it home and started to tinker with it i dropped a battery in it it turns on fine and turns over but will not start so i checked the spark and there is no spark so assumed crank position sensor.. so i changed the sensor as well as the timing belts. put it back together and still no spark so i plugged a handheld OBD2 code reader in to see if there were any codes.. this is where it got wierd... when i plugged the reader in the reader turned on but when pressed read codes the speedometor climbs up and pegs to 140 MPH and the actual miles of the car start to climb as if i were driving 140 MPH down the road even though the car isnt running and the code reader will say unable to access computer once i unplug it the speedo goes back to normal.... this is what stumped me .... i read in my manuel and it says nothing about this and what im wondering is if it could be the ECM/PCM? or is this a short somewhere? or is there a bad sensor somewhere causing this?? any suggestions would help!!!!

Thanks,
Mike