new fuel pump - ran great for 100 miles - same problem

Installed new fuel pump in turbo valley,
purged air out of system,
truck was running great....

for 100 miles or so... then stopped pulling fuel to bowl again...
if i can keep fuel coming to bowl.. truck runs great..
im thinking there is a clog...

any suggestions?

also, which line would i disconnect on top of fuel pump to send air back to tanks to check for clog? ( i know low pressure )

any help... pleas... i am supposed to take a long trip this thursday 500miles..
and im a lil nervous..
thanks

Ryan in Ithaca NY