P0505 Honda - and 31.2

Question

2001 Honda accord 3.0. Idles at 900 then both the tsc and check engine lights come on at same time, code po 505 idle system and abs code 31.2 pfinh signal failure. I have replaced the iac valve, cleaned throttle, checked wires to ecm, iac seams to be working, speeds up when you un plug, if I close the hole in bottom of throttle it will idle down, also removed egr valve all looks good. it will idle for a half hour at 900 then the lights will come on and idle at 1300, some times if you give it gas and let off it will surge between 1300 and 1500. also have a complaint about the instrument cluster gauge lights coming on and off while driving I don't know if that is related or not, {Ignition switch?} the only thing I see on my scanner is the retard function. it shows failed, I have checked for vacume leeks, I did look at the base idle screw to see if someone adjusted it but it was fine. any Ideas if the code 31.2 could be causing the idle problems. or crank sensor. thanks