Hyundai I 10 with electrical problems

Hello friends, I have problems with a Hyundai I 10
The vehicle works well and begins to pull is not continuous are only pulls when you change the most frequent march in the 1st and 2nd and sometimes the engine stops on the board only the witness light of the safety key is turned on.
Take it to scare and throw ignition coil.
I change coil, spark plugs and cables and the problem continues.
Clean injection and remain the same.
Check a battery, alternator and they are working well, they tell me that it can be a ground cable or some plug and finally a relay, I do not have the electrical scheme to be able to follow the current step by step if someone has it and can make me arrive or if anyone had similar problems and have some data to review.
I would appreciate them very much.