Glad for health recovery of your truck.
By the way you didn't need to change the coil, in most of the cases the ignorant mechanics don't know the problem and they are Keen to put solution tape on coils because they don't know anything and they have to show the customer that they did something.
Do one thing. Take off the solution tape, and out the coils back. Since injectors are already changes and your truck is starting in good health, so start the truck in old coils. If it stays the same then keep the old coils and return the newly purchased coils. Save yourself from tricks of mechanics.
For check engine light, share the codes here.
Your mechanic is a rip off and I would kick him between legs for saying illogical stuff. These mechanic ustaads are cruel as f**k. He doesn't know what he is talking about. Put the old coils back and share the codes here.