Nissan Repair: 1997 NIssan pickup base model short cab, fuel pressure regulator, nissan pickup

Question
I was driving my pickup the other day and I stopped at a red light.. When I shifted to first and took off it almost felt like the clutch was going out. I then shifted to second and felt the same jolt.. I successfully got to 5th gear and would and every 5 or 6 seconds it would jolt again. I however work in a body shop so this morning I asked a friend about it and he told me I had got some bad fuel.. I bought a fuel filter and replaced spark plugs and wires. I also drained all the fuel and replaced it with STP gas treatment along with about 5 gallons of unleaded regular gas.. However the jolting still persist. While sitting in neutral with the truck running if you press the gas and bring it to 2500 rpms it bogs down(does not cut of)It just jumps from 2500 to 3000 or so rmps back and fourth.. There is a black smoke that comes from the exaust? Any help would be great!! Thanks  

Answer
Brett,

If it is not the fuel then it is the spark.  So, first check to see that the fuel pressure regulator is working and if it is check the distributor for oil on the optics.  The internal seal in the distributor fails and oil gets up on the optical shutter wheel and that causes the engine to cut out and the fuel to load up.  So, if the regulator is not defective causing the over rich condition the cutting out of the ignition will cause it too.