ok guys have couple questions, i did a self test on the ecu and it shows that all 4 coils are firing and all 4 injectors are also firing,

Is it posssible for the 4 coils to fire if the x4 box was bad?

also after the self test the red light remains flashing does that means there is a problem.

the problem im having is that the car wont rev like it was before and its starts like breaking up around 3000 rpm, also every time i pulled the spark plugs the plugs are very black mainly the L1 and T1. i swaped the msd coils for 4 trailing coils and still the same.

really getting upset over this issue, car was running fine and the 1 day after getting it tuned it started with this issue.

 

Check your fuel pressure? id say thats your problem. Either bad reg or fuel pump

 

Kinda sounds like a voltage issue

 

it was a faulty injector on front rotor, i guess it was stuck open or its leaking,