ok my friends car is running like crap...its the EB2 with factory gas system

i suspect that its the stepper motors on the convertor have gone bung...

is it posible to fit a power valve and adjust idle manually on these with a few mods?

You can just take the stepper off and fit a power valve to it, just tuck the loom away... No mods needed to do that.
If it's running crap then the convertor could be a big part of the problem, if it's rooted then throw it in the bin and buy an OMVL R90e.

i told him the convertor is most likely fubard and to replace it with a different brand but its a bit of f**k around with new brackets and shut off valves and the line....

car is really not wanting to rev, and missing and backfiring.....it was running alright before but now rooted