isx problems

hi.i have an 07 9400i isx 435 turned to 500 hp.everything opened up.1st question is,while sitting parking brake engaged,i rev it up.it stays at 1500 rpms no matter how far I push the throttle.after a few seconds the speedometer goes to 20 mph.and will then rev to 2100 rpms..........2nd question.being that the truck perameters are opened up.it will only go between 1550 and 1750 while driving.really annoying while trying to shift. then flat line.like its restricted .sometimes it will open up and turn 2100rpms.and really come to life.can someone help.this is my last resort before going back to a cat.thanks

 

I forgot.i can not set the idol while sitting still.but the cruise works

 

thanks for your info.all of the safety features in the ecm are turned off.it is opened up all the way.guess everyone is stumped like me.lol.......