1989 Ford F150 v8 F150 running rough

We own a 1989 Ford F150 v8 with 150000 miles. The previous owner never did a tune up or oil change in the 2 years he owned it, before that we have no idea. Here in the last two weeks it has started to miss and the fuel smell is so intense it has to be running too rich. We have changed the plugs, wires, cap and rotor, fuel filter and air filter. We have checked the timing. Changed the oil. Checked the vacuum hoses. Everything we try or replace it seems to run worse than it did before. We are at a loss as to what to check next. As of yesterday morning, leaving for work, as we were taking off from stop signs, the truck would stall, then start to shake tremendously. Also, the check engine light flashes three times and then goes off when you start to take off or sitting in idle and revving the engine. Any ideas as to what the problem is?

Have the fuel pressure checked. Sounds like you may have a fuel pressure regulator that may be failing.