Hows the compression?? Also check to see if the timing belt has jumped a tooth or 2 If it's blowing fuel smoke out the pipes, check the mixtures.... this sounds rich to me.. When the gas peadal gets pushed down does a lot of smoke (dark smoke) Also I'd look at the ecu, if those go bad they can cause such problems along with o2 sensor, are any wires burned or grounding out. Or maybe a patato got stuck far into the pipes..... or maybe a dead animal or snakes....?? hope some of this helps good luck. keep us posted.. cheers