air leak on the vacuum tap?... (that's the only thing a Raptor conversion could do to make that symptom)...

I believe that a rotted fuel line will cause it as well. Do you smell gas?

just ride to the parts house, pull it off, walk in, buy some, fix it,,you'll feel as victorious as john wayne savin the PILL Grumms..

NO! If ya do that, then youll never need to ride to the store & change it in the parking lot again,, you wouldnt want that, now would ya?
as for size/diameter,, IDK it,, but if ya walk in with it..

Silicone isn't exactly the easiest line to find, unless you have access to a good late model import car "tuner" shop. Pep Boys and O'Reilly tend to have it, but not necessarily in the right internal diameter... You really need to go to a specialty shop for it. Or order it off the internet...

And what you ended up with is still higher quality than the factory installed piece. Mine shipped with thin wall tubing, more commonly called vacuum line, as fuel line. Didn't hold up well to the climate on the Gulf Coast.