Randomly the engine will idle funny and the check engine light comes on. The n it will fix itself and eventually do it all over, I did the key on-off trick and got 12 27 codes.

12 Battery or computer recently disconnected

27 Injector circuit isn't switching when it's told to (TBI)

which doesn't make sense since I haven't disconnected the battery or messed with anything like that, unless I read the code wrong. I did twice to make sure, but any help?

 

Clean your cables check grounds simple stuff bud