I have a 94 Suburban 4x4 with a TBI 350. This thing runs good until you shut it off after it warms up. Once its shut off and started back it runs like sh*t for a few minutes. It shoots out a big cloud of smoke when you give it gas. If I keep my foot on it it will finally start running good again. I have checked the timing, new plugs and wires, distributor, timing chain, fuel filter, and also a new throttle position sensor. I am about to my end with this thing. Any ideas on what it could be? Or anything else I should check?