Why? Is the motor running badly? Mis-fire? "Stagger"? Anything like that? If not, why fix something that ain't broke?
Not being the mechanic-whiz that i thought I might be, if I had a problem with the motor and could tie it down to the injectors, I would first use one of the commercially available store bought products. If that didn't clean things up, then I would seriously look at removing and cleaning them. Then...I would look at how much would it cost to remove, clean and re-install vs. replacement. (Do your own work? Then that's a moot point)
Maybe something simple for a 1998 motorhome (or ANY motorhome, really)...just take it for a long 60 mph drive. Maybe that's all you need.
g'luck!