2017 Mercury 90 hp 4 stroke popping and won’t go above 4200rpm

Hey guys needing a little help. I have a new to me 2017 Mercury 90 ho four stroke CT out board on a 22 ft sun tracker pontoon. It runs very rough at idle and won’t go above 4200 rpm. I also get a semi loud popping sound on acceleration and de-acceleration (2500-3500 rpm) and sometimes while cruising. I’ve replaced the fuel with known high quality ethanol free gas, replaced the fuel pump assembly and filters, cleaned the injectors, checked all the fuel lines and replaced the spark plugs. It does run some what better after all this but still doesn’t run well. I’m wondering if someone might know what I should do next or what the problem is? I have videos of the problem but can’t seem to get them to post on the forum. Thanks in advance for the help!

Don will need your serial number. Has the engine ever performed as it should under your ownership?

It has never performed the way it should. Bought the boat and motor last year and have been fighting it ever since. Serial number is: 2B422925

when you say popping do you mean a mechanical pop like metal on metal....or a backfire exhaust type pop?

Also- a couple more questions:

1. Where are you obtaining your RPM info from ? Smartcraft or an Analog/needle Tachometer?

2. What prop is currently on the engine (exactly)? Any damage to the prop?

3. Does the warning horn sound a test beep at key-up?

4. Any warning horns while running?

Pop is definitely not metal on metal more back-fire exhaust type. Rpm is coming from analog tach in the dash. Prop is new with no damage(replaced last summer with a black max, picked it up from tracker boat center its the Prop they recommended not sure on pitch it’s a 3 blade though). I get one beep when the key is turned on and no other warnings or beeps when running.

Has the engine ever run properly at WOT since this propeller was installed?

And if not, DID it run properly PRIOR to the propeller replacement?

Sorry for the questions, but Analog tachs are notoriously inaccurate and we need to make sure we're not spinning the engine higher RPM's than we "think".