Welcome to JustAnswer, my name is XXXXX XXXXX I'm here to help get your problem resolved. Ask follow up questions, thanks.
All you can use is injector cleaner that goes into the gas tank...Otherwise it needs to be hooked up to a special machine.....If vehicle is running rough or misfiring its more likely a coil as these vehicles have alot of coil problems....If you know what cylinder is misfiring you can swap coil with another cylinder to see if misfire moves, if so replace coil.
would the fuel injecters need to be replace if the have alreay replace the coil?
Stinks he wasnt willing to be straight forward with you and fix his mistake...at least you know not to go there again.....Driving it until it runs better is a lie......Let me know if you run into questions, thanks.