Well I can't help you on that one, someone here surely can, but I would think that if you have done all the cleaning disconnecting the tube at the engine end and having someone turn the key would have the pump give you fuel that you could collect to see how well the pump is doing. I mean if you get a half gallon in a short period you can see how productive the pump is. After that I would try maybe some injector cleaning fluid in the gas. I have no clue on cleaning the existing injectors @DannyP