Toyota Repair: 93 Toyota Pickup Erratic Idle, throttle position sensor, vacuum pipes

Question
I have a 93 toy P/U with 194k miles... 4 cyl 22re engine. I have an erratic idle problem where the engine revs itself up and down up and down at idle.  The problem also happens when the brake is pressed sometimes.  I've replaced all vacuum lines.  I've removed egr and tested it with a vacuum pump and it is fine.  Replaced throttle position sensor, coolant temp sensor, thermostat, and radiator cap.  The car also will blow cold air when the heater is on, even after driving the truck for over 30 minutes on the freeway. I'm kinda running out of ideas to fix this problem.  Could it maybe be a intake manifold leak or an air bubble trapped in the cooling system?  Please help!  Please email me if you need any more info on the truck or the work i've done to it (Which isn't anything other than normal repairs, no performance mods).

Answer
Try to make sure that there is no leak in the intake manifold. check vacuum pipes. Air bubble in the coolant has nothing to do with the engine idle if the engine temp  is normal. Check all other items related to combustion.
check the valves for proper operation if the heater is blowing cold air.