So this is a little issue that has been bugging me for some time and I am just now trying to find an answer. Google and the forums search have not turned up a result that I can find. The issue is with some aircraft (for example the default 737-800) when you start the engines, once they actually start the power jumps way up before stabilizing. I have the power levers at idle so that is not the issue. Any way to fix this?

That isn't a bug. That's misscoded by Microsoft. But some addon planes got it right.

So any ideas as to what some addon aircraft did in order to get it right? Is it something that can be edited?

So any ideas as to what some addon aircraft did in order to get it right? Is it something that can be edited?

Editing from your side ain´t possible (except your a developer and know how to overcome that.). you could get the new PMDG 737NGX. There the startup will be exactly like in real life.

I have found that doing a manual start as opposed to using auto start solves the problem.

Are your fuel switches already enabled when you start the engines? In other words do you simply turn the ignition and the engine fires up, or do you turn the ignition then wait for the engine to reach around 22% N1 then turn on the fuel pumps? The latter is a better idea

In efforts to save time and simplify a few things I had just been using the simulator's auto-start command and let it do its thing. On the aircraft I flew the most this was fine and I had no issues, but on others (such as the default 737) I was getting the really high power immediately after start. Once I started manually starting it (engage the starter, let the engine spool, and then close the fuel shutoff) it started like it should. Guess I had been a little spoiled by some aircraft starting like they should using auto start. Its all good now.