the main difference between gas and diesel is the lubricatiating properties, Gas has none. one thing I would do is drain the injection pump that has a roosa pump there should be a window on the side of the pump with two flat blade screws remove the window and let the pump drain out if there is a lot of gas comming out you might have problems. what you discribing sounds like a fuel supply issue but I am afraid your pump might be bad. I don't think the gas hurt the injectors but it could take out the pump rotor head fast. if you have good fuel supply with the change in rpm and loss of power when hot I would say your pump is bad. I would go for a reman exchange pump if you rotor and head are bad the repair cost will be more than the exchange price.
Good luck Ed