its dumping fuel you have a fuel related isssue, check injector o-rings, easiest way is just pull the fuel rail and have your buddy turn the key so the fuel pump kicks on but dont turn it over while you hold the rail if it leaks fix it, if not you probly have a bad sensor or ground somewhere causing it to dump fuel. the coolant temp sensor could do this. and if you have a vacuum leak it would run lean because your sucking in more air than the computer sees so your getting more air than fuel and you said your running rich i.e. more fuel than you have air for so your either leaking fuel into the cylinders or the computer thinks it should dump an assload of fuel for some reason