Figured I'd get more looks here than in Boats & Motors...

Motor is a 2004 Merc 3.0 liter 200 EFI on a Triton TR-196. Starts and runs great off the trailer but after it's been running a while (20 -30 min) and and you turn it off to fish and it sits an hour or so it will start restart fine, but it bogs and eventually dies trying to get on plane. After it dies it usually won't start again for over an hour.

Thought it was possibly air in the fuel system since a lot of it was original. So far I've replaced lift pump, high pressure fuel pump, all fuel lines, fuel tank fitting and primer bulb. Took it out last night and it did the same dang thing.

Ideas to try? I've about had it with this thing.

Sounds like it's starving for fuel. Is there a vent on the gas cap or in the filler neck? Many years ago I had a Mariner 40HP with a portable fuel tank. If I didn't remember to vent the fuel cap, the boat would run great then eventually die. It was pulling a vacuum on the tank when not vented. I dunno, I'm not a mechanic. Just skatter shooting.

Have same motor 2003 id check the fuel pump inside the vst.if you buy a new one make sure it's a merc part big$$
The aftermarket ones will get hot and boil the fuel.

I think Bob is on the right track. Research Outboard Vapor lock. I bet that is your problem

I did think about the VST. I checked the filter screen on it and it was clean. You're right, OEM isn't cheap.

The vent is in the filler neck. It seems to be fine as far as I can tell, No problem putting gas in the boat.

break out another thousand.

carb rebuild

first replace the gas, add some star tron and see if that helps.
otherwise, what Bob said ^^

it's fuel injected...

I have a 2002 doing basically the same thing and it’s had 2 different shops throwing parts at it for 6 months now. Mine definitely isn’t a fuel tank or venting problem, I strapped a 12 gallon auxiliary tank on the back deck and it did the same exact thing. Runs perfect first run off the trailer and the rest of the day it’s a dog.

gas these days is the worst.
try the flush, it worked earlier this year on mine (also injected)

Bad plug or plug line?

PM sent

Sounds like vapor lock. replace fuel cap and replace tank vent line and filter.

Hell, just keep throwing parts at it. You’ll find it eventually.