So I run a 2002 with a smart set on 3 everything else is stock.

I was putting across the yard the other day and it started chugging and couldn't hold rpm. I immediately backed it up to the shop and shut it down. Now the only way to start it is to bleed the fuel lines, and even then it will run fine for 5 seconds then start chugging and quit. I have already replaced the fuel filter and the old one looked perfectly fine. Any ideas? Hoping it's not the Lift pump.

 

Whats your fuel pressure? With no fuel pressure you are staving the VP and will end up having to replace that too.