1995 Suncruiser RV. Engine has almost no power.

[SwampDonkey88]

Engine starts rough and runs rough until warm then sound good. But when I take off in it there is little power. It does seem to want to build power as I go but quickly abandons the thought and she goes right back to being a gut less wonder. It never does get goin faster than my brothers electric scooter. I have replaced the plugs and wires, the fuel filter, filled the tranny fluid, all fluids for that matter, and need some guidance. She must be running asap as the folks who own the property I'm on have respectfully asked me to vacate. Someone said it might have to do with a "fuel shutoff switch"? Does that sound right? Please help!!! Thanks

 

[Zoohelp]

You didn't mention which engine you have. First I'd see if you can get an engine tester hooked up to it.
Have you checked the fuel pressure at the rail when warmed up? Should be 40-45psi with key on engine off. If not, it could be a bad fuel pump
Possibly coil/coils on the plugs.
Those would be best starting points

 

[Winn2021]

Engine starts rough and runs rough until warm then sound good. But when I take off in it there is little power. It does seem to want to build power as I go but quickly abandons the thought and she goes right back to being a gut less wonder. It never does get goin faster than my brothers electric scooter. I have replaced the plugs and wires, the fuel filter, filled the tranny fluid, all fluids for that matter, and need some guidance. She must be running asap as the folks who own the property I'm on have respectfully asked me to vacate. Someone said it might have to do with a "fuel shutoff switch"? Does that sound right? Please help!!! Thanks

If she's not been out and about for a while, bad gas may be a contributing factor. Ethanol absorbs water like nobody's business and the older gas engines weren't designed for it.

 

[Morich]

This is one where I might go for a pro job to lookit over as a way to save money long term. Hooking to a machine to tell what all the small parts are doing can lead to tuning that can save money over DIY if we don't have the tools and machines to give a full picture! Lots of small parts that I can't even begin to name and they have to open and close at the right time to get the best value! Something as simple as a leaking vacuum line is one I might never find!
With gas prices going crazy high, it doesn't take long to flush dollars down the drain.
I'm guessing six dollars is here before August!