Hi I am trying to solve a low idle problem on a 94 4runner. Right now it idles between 450 and 550. It doesn't stall at stops, but it does idle very rough. I would like to get it to Idle around 700 to 800. I have done the self test on the computer, but I am not getting any trouble codes.(checkengines light just constantly flashes) Can anyone give me any sugestions. I have tried to manually adjust the idle but after a few minutes the computer overides it and it drops back down.

94 4runner 4cyl 22RE
manual trans.
AC
K&N air filter