another speedometer/check engine light problem
 

yes i did search... didnt find anyone with a similar probem

the speedometer works fine.

but under sudden acceleration or decceleration, the engine check light comes on. its the code 6 speedometer i believe.
it also happens in the morning when the 3k stumble occurs. (stumbles every early morning soon as the car warms up, go figure)

now if i had a loose wire, would the speedometer still work?
or if the speedometer is failing, would the check engine light come on before it fails?
or is there a ground or perhaps a fuse that has gone bad?