Possible mechanical issues: junk in fuel tank causing clogged fuel intake and/or fuel filter, pinched fuel line, open fuel line connection (probably 'tween lift pump & injection pump) that allows sucking air into fuel, injection pump going bad, lift pump going bad, clogged fuel filter way past its service interval.
Possible electrical issues: bad connections including clean, firm grounds (lots of these to check), chafing wire looms.
IIWM, I'd change fuel filter immediately as advised above, and cut open the old one to see if it is clogged. If not, do a full visual for signs of fuel leaks, pinched lines, etc. Then proceed to wire loom visuals, then electrical connections. If you can't find it yourself this way, you'll need professional service for additional checks on lift pump performance, etc.
Baja-tested '08 2-slide 36'
Alpine: The Ultimate DIY'er Project