Vaccum leak?

So i have a bone stock 2012 speed3 with 80k miles. For 2 months now it has had misfiring problems which trigger a p0300 code , ive noticed on my ap that my map volt at idling is 0.30v and when accelerating it would only go up to 0.50v, i replaced the sensor and its still reading low map volt , also did a datalog when it was misfiring and saw my stft shoot the way up to +25 whiles my ltft stay at -3 , any help would be appreciated


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What is your ltft at idle with AC off and during cruise. Because -3 during any of those times is great

 

Well during cold start stft reach +10 whiles map volt only peaks at 0.48v after ut gets warmed up it settles at 0 stft and 0 ltft but like .20v map volt , also noticed during deceleration map drop to 0.8v which makes the car misfire and shoot stft to +25 . Sorry for late response


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You can't rely on STFT readings during decel because as soon as you lift and start to decel the ECU shuts the injectors off so it doesn't wash down the cylinders. You can see this happening if you look at your MPG gauge going to 99 mpg and the AFR reading will go full lean. This is normal

 

Cold start is whatever it's adding fuel to warm up faster. If you're idling warm at 0 ltft that's pretty amazing! You only answered half of my question What's it if your crusing at say 40-60mph (60-100km/h)