Quite an easy problem to solve by the sound of it.

Find out why the RC valves don't work. I suspect blown PGM. Then find out why the PGM blew. Dodgy servo, cables too tight, gummed up valves. Sort that out and then replace the PGM.

You'll probably get your smoothness back from idle to redline.

Failing that, manually close the valves halfway and see what happens. If it's more like you want then keep it like that and cruise around, safe in the knowledge that you're enjoying maybe only half of what the MC18 is all about.