The MAF CO adjustment may have been set very rich to compensate for the leak. Measure the resistance at the MAF between pins 6 and 14 at the LH connector (or pins 3 or 4 and 6 on the MAF). The 'zero' point is 382 in a 0-1000 ohm range.
To set/check the idle, put a piece of wire between B & C on the engine diagnostic plug to stop the automatic idle control. Turn the idle screw CCW (out) to raise the idle speed to 700 rpm.
