Engine\'s smok\'in - Need help! The '88 350 is stock, it idles just fine but as soon as you put it in gear it loads up and starts blowing black smoke out the exhaust. We've changed plugs, wires, cap, rotor, and O2 sensor. Someone suggested it might be a faulty EGR valve, what do you guys think? When it idles it's very smooth otherwise. Is it worth paying $50 bucks to get it analyzed?