Negotiating several problems with the 4.3 cobra. With this one the engine wants to die when on plane above 300 rpm. I can throttle back/or to neutral and the engine kicks back to life. It sometimes dies completely and I can restart fine. Its got me puzzled. I have checked vent hose. fuel return hose from carb, fuel water separator and fuel line connections. I drained and completely dried the fuel tank(built in tank) last year and check for debris and h20 and found nothing.