I've posted before about the engine troubles I've been having with my Malibu. 335 monsoon in a sportster lx, occasionally it will bog and lose power, giving it more power just causes it to backfire. Pull to neutral, idles smooth, pull up again and it runs fine, most likely will do it again though. It doesn't do it cold, only after running for about 30 minutes or more.
I started with the easy stuff, cleaned out the inlet screen on the fuel pump (external pump), changed the fuel filter. Then pulled the tank and cleaned it out, replaced the anti-siphon value, new fuel lines. Still doing it so I replaced the fuel pressure regulator, still doing it.
Put a fuel pressure gauge on it and it reads 5psi at prime, 35 at idle, 38 at ski speeds and just over 40 above 40 mph. when it bogs the needle is shaking but that could be because of the vibration of the engine while bogging, but there is no noticeable change in fuel pressure when it loses power.
Do I just suck it up and put a new fuel pump on it (it's about 300 bucks for my model), or do I start looking else where? Ignition maybe? I'm pretty much out of ideas so any help would be appreciated. Thanks guys.