I have had my 1991 Ford F-150 4.9l for about 2 years. It has always been hard to start. I did all of the tune up stuff but nothing seemed to help. It has gradualy performed worse and worse.It would buck, surge, and hesitate. I was told by some that it was possibly the cats. I had them tested and they were fine. Occosianly I would put in injection cleaner and things would improve some what for a while. Finally it got to the point where it would take many cranks to start. When it finaly did start it would idle fine but start to bog down and backfire when I would give it some gas. It got to the point where it was no longer driveable. Long story short. It was the fuel pump. It was getting gas to the engine but the system was not pressureizing. Now that I have replaced the pump it starts right up and performs better than it ever has.

 

I did the same thing except I replaced my regulator. It went from taking 2 tries to crank (granted only 3 seconds of actual cranking) to now cranking IMMEDIATELY (1 sec). What a difference.