I've only had my CEL come on once. My truck has 113K on it. It was the A/F ratio sensor that was the culprit. My feeling on yours is also the MAF. The cam timing isn't the problem. Toyota makes timing belt replacement so easy a monkey could probably do it and not get it wrong. The best way to look for an intake leak is to smoke test it.
BTW, I'm selling a OBD II generic scan tool.
http://forums.pelicanparts.com/porsche-911-used-parts-sale-wanted/667393-f-s-obd-ii-scanner.html