You definitely dont want it plus, was it cold or warmed up first off, and what size injectors are you running? fuel pressure? I still think you got a vacuum leak or throttle not physically shut , dash pot hung up or something, the mainscale is only changing your idle because it was choking it to death with fuel. You gotta dig and find the idle problem first, some years have a screw adjustment on t/b, pull the throttle towards closed manually at the butterfly while its running, see if it moves and idle comes down, spray carb cleaner around intake manifold gaskets, any vacuum hoses, anythiing on intake side, if rpms jump up where you spray, thats were you have a leak. could be vsv hoses, brake booster, hose to bov, fuel press reg, so on.
