Throttle won’t accelerate past 3/4 slight surge

Quick back story bought a 1990 Ski Nautique 351w in 2016 prior to me buying it it had a protec EI put in was ran some and then sat 2 Year’s (due to previous owners passing away) after I bought it we discovered that it was not running on all cylinders. After changing the plugs and having a compression test done(everything was ok) and the timing set. Took the boat out shortly after that and experienced a poping In the carb and hesitation or stall on launch. Sent the carb out and had it rebuilt. Fixed the problem with popping but not the launch issue. So I decided to get a new carb and switched from the 600cfm holly to a 600cfm quick fuel. Upon doing so the fuel line did not line up so I had to change to a slight longer flex line. Took the boat out again and it ran beautiful for about 2.5 hrs then when cruising upstream the engine just cut out ( like someone shut the key off). So I took it and dropped it off at the marina to see what the issue was . Turns out the gear on the bottem of the distributor sheared off. So I got a new distributor installed and he also decided to use the electrical tune up that I had already bought previously just to have on hand ( coil, rotor, distributor cap, plug wires, fuel water seperator) and it was re timed. Took the boat out yesterday to test and see if this distributor was going to shear off. (It didn’t) the idle is set right around 900rpm when at very low speed it seemed to surge slightly then ran great in mid range up to 3000rpm cruising. Once I try to go any faster / beyond 3/4-7/8 throttle I get nothing no rpm increase no speed no power however the boat surges ( I think that’s the word to describe it ) and feels like it wants to give more but can’t. The carb is still factory set idk if fuel/air screws could effect only the low and high end. Or if it was something more like and air leak, fuel pump /filter/ line issue or something I’m not thinking of any feed back is greatly appreciated and thank you all in advance. (Also happy Father’s Day to any dads out there )

Got kicked off somehow.   QF carbs right out of box without issues.   Check carb base gasket for tears and adapter plate it sits on. Some types gaskets don’t seal well.   I’d also verify you are getting full throttle cable stroke at carb without it running.   You could verify secondaries are fully opening but I think something else is going on before you get to this point.

Last thing idle should be 650-700 rpm in gear

The boat has an electronic ignition in it sorry if I forgot to mention that. And the flex line is uscg approved it’s the 25” flex line that other qf users have recommended from skidim I will check the throttle cable and for any leaks around the base plate also will take the hose off and make sure nothing is instructing flow

Let us know how it goes.

Thanks again for all of the feed back I’m hopeing that’s all it was I’ll forsure repost this evening when I get her on the water 🤞