Fuel pressure

The truck was dying at red lights when you take
your foot off the gas I took it to a mechanic he said
the throttle positioning sensor a place that myself
it stopped dying at the red lights but then it started
dying while going down the highway and would not
start back up sprayed ether in it finally started up
so I replaced the fuel pump it did it again manage
to get it started had to spray ether and pump the
gas and I know it's fuel injected shouldn't have to
pump the gas so far I've replaced the TPS and the
fuel pump and put some fuel injector cleaner so
what's next pressure regulator I really don't have a
pressure gauges and other diagnostic tools or
money so any advice would be greatly appreciated