Hello. The fix to this problem sounds very complicated.......but it is not, just time consuming.......

First thing to do is fix a container under the hood to hold about a half gallon of your favorite injector cleaner (this is more so to clean the internals of the IP) remove both the fuel inlet hose and the fuel return hose and place them in the container........crank the engine and use up almost all of the cleaner and in this time rev the engine up several times as well as turn the engine off and restart several times..........

After this, remove the injectors and clean the injector port in the head of carbon (should be about a 5/16 to 3/8 clear hole)......cleaning the injectors and setting the pop off pressure is a excellent idea at this point........reinstall the injectors...........

Now starting at the IP where the metal fuel line connects, remove the banjo bolt and clean the screen, remove the fuel filter mount and clean it (it has a one way valve in it, make sure that you can only blow one way through it....................new fuel filter.........

Now remove the fuel tank top and blow compressed air back through the fuel line to the tank.

Replace all fuel hoses with new clamps as well............

Fill the new filter and hose to the IP with fuel.............

Start the engine and go for a long drive......stop......and immediately loosen the fuel tank top listening for a "rush of air" into the tank.........if so, replace the top......

If the problem is still there.........on the fender well side of the IP is the Cold Start Devise.......you can best see it from under the fender well.........in the center of the CSD is a round plug with a 11 MM allen...........remove the plug.........there will be tension on the plug.......be careful of the shims and spring....................remove the spring and shims and reinstall the plug being careful of the "O" ring.................now on the top of the CSD you will see a banjo bolt and metal line that goes up to the fuel return hose..........remove the banjo bolt and clean it out..........go for a drive and vary the engine rpm a lot.....................now reinstall the spring and shims........................you May have to repeat this a few times to free up the timing advance....................

Set the IP timing...............

enjoy,
crossbones