91 Celica GT idle erratic

Hey Guys... I have a 91 Celica GT automatic. It has 150,000 miles and still going strong. Has a lot of know parts and money invested in it. Need it to last me one more year of college. But I have a very annoying problem. My idle is erratic. Has in my rpm's bounce up and down when I'm not moving. Sometimes I have to hold the brakes and give it gas in order to stop it from stalling. I've replace the head gaskets, new plugs and wires, air filter and all the hoses (on throttle body, vacuum, etc.. I have found the problem to be that in the throttle body itself there are 2 ports that are sucking in way too much air. It makes a horrible sucking noise. Not normal. And when I put the air filter on you can hear the noise resonate even worst through the housing. When I first apply the gas it start to suck in air normally without the sucking noise but then quickly start to act up again. Thus giving me the inclination the there has to be something wrong there. I can't see anything problem on the exterior. I have basic knowledge of my car and can't fix it any further. I've taken it to two other mechanics. One tried to fix it and couldn't. One did for about a month and he didn't do much. I've taken commercial places and they are charging an arm and a leg just to run diagnostics on the engine plus $75/hr labor and parts!!! I'm a college student with too much debt. I was wondering if anyone had the same problem or could possible help me out. If I can't fix it I plan on taking my baby to a pro but I want to know what the problem could be so I don't get ripped off. Here in FL they are all crooks!