2004 Nissan Titan lost power-startedonce-wont restart

2004 nissan titan pulling a trailer labor day weekend running fine, then started loosing power but still idling, pulled over shut engine off restarted put in gear but no increase in tach just idle when depressing pedal, shut off again and would not restart. I had it towed to mechanic he felt most likely a fuel pump replaced it but did not help same condition, also sprayed engine start wouldnt fire, the engine does turn over but doesnt try to start, but makes sense no fuel from tank being pumped. Tech tested injector it was not active either. I read a lot about ipdm issues so we decided to order one after new ipdm installed same issue no fuel or injector results. Hopefully you have some suggestions