Hi @gtb0331
I’ll throw a few things in here. Some you may have already figured out or done.
First, don’t use carb heat in a climb (or if you have to, you’ve really put yourself in a bad place and all is lost anyway! 
). I’ll let you look around some more on that subject, but in general, carb heat is most useful on warmer/humid days, when reducing throttle for descent or landings. As always, some exceptions can be found…
What most worried me was that you’re only getting 2300 RPM!! Is that what you have when you start the takeoff roll, and are you taking off at high altitude airports? At sea level, you should be able to turn ~2500 RPM, and it really shouldn’t change much as you climb out. I tried it using manual leaning, and lean assist and didn’t get too much variation in results. From the screenshots, you can see that I kept ~2500 RPM all the way to 8000’ MSL. Once I’ve leveled out at 8000’, I pulled the throttle back to keep it out of the red.
So, next. Are you trying to maintain a constant rate of climb as you go up? That will definitely cause a stall in the poor little 152 going to anything over ~2000’ MSL. You should climb at a constant IAS and just let the climb rate (VS) drop off as you go higher. Some will say to climb at best rate-of-climb or best angle-of-climb, but (and this goes back over 50 years!) for an extended climb in the 152, I normally used ~60-65 Knts IAS to help with cooling the engine during the climb. But it’s just a sim, so can use anything above stall speed (and keep it at that speed!) that gets you where you want to go! Keep in mind that increasing bank angle will also increase stall speed, so watch your bank angle at climb/descent speeds!
Double check your pitot heat is on or it will give you false airspeed readings sometimes. Make sure your flaps are full up after takeoff (that won’t change your RPMs, but it will affect your ability to climb).
So first check why you’re only turning 2300 RPM, because that’s a real issue! If you’re relatively near SL, and still only getting 2300, then we need to work on that issue first and foremost. The other stuff will apply once you’re in the actual climb.
Regards
First shot, just after T/O turning ~2500 RPM. Starting extended climb to 8000’ MSL. Note the VS is not realistic for more than a few seconds. It jumped on me a bit taking the screenshot!
152 just reaching 8000’MSL. Please note: the VS again jumped up to an unstainable rate for that couple seconds I reached over to grab the screenshot. I really need to set at macro to get shots!! It will not maintain that rate at 8000. If I’d left it at that rate, the speed would have bled off quickly!
Third shot, pushed nose over to level the plane, let the speed build a bit, then pulled the throttle back a bit to keep the engine in the green.
