E150 running TOO rich

[mrcards]

I have posted messages previously about my E150 conversion van with a 351 motor running too rich. It was running GREAT until one day it started running way too rich.....hardly any power and poor gas mileage. The engine code is flashing 51. I replaced the O2 sensor,the coolant temp sensor and the air temp sensor which according to Ford's manual are the causes of code 51.
The van runs a tiny bit better, but still codes 51 and runs like a dog on hills.I thought maybe the cat convertor might be clogged. Anydody have any ideas??If you've ever driven an older carberated 351 with a choke problem that is EXACTLY how this stupid van is running.Ford doesn't know what to tell me. They want to replace this and replace that until they get it running-which is not the kind of mechanic that I am or was taught to be.Any ideas would be greatly APPRECIATED....

[Racerguy]

I would check the fuel pressure. You quite likely have a bad fuel pressure regulator.
You can also pull the vacuum hose off the FPR and check for gas in there. If there is gas in there the FPR is shot.