Paccar mx13 epa13 coolant in fuel!!!

[Colter]

Pull your injectors and pressure test your cooling system (to 5-psi only), that'll confirm a leak at an injector cup(s), I wouldn't replace cups unless you feel like doing this again within a year,

Personally I would replace the head, it takes no time to do but parts will be higher obviously, itll take the same amount of time to pull injectors as it would to pull the entire head, if its done by a competent tech it won't/can't take more then 16hrs, it'll cost 2-3 time more then cups but you'll be running without issues for a long while in comparison.