SG
Here's a general answer to your question:
First, you have to accept the AI of a given sim when you engage an AI-flown adversary. The AI may or may not be 'realistic' or reasonable, but that is irrelevant. You just take what you get...if you don't like it, then go to another sim.
Having said that, there is an approach to take for the conditions you describe. If you cannot climb up to engage the bandits on equal terms, then remain at your altitude. If an engagement seems inevitable, you want to deny the bandit lateral turning room. Do this by following the bandit...try to remain under his flight path...do not let him get off to your wingline on either side.
If the bandit is to engage you, you want him to have to dive directly down on you. Use your snap view or padlock to fly under the bandit. Keep your airspeed up...at least corner.
Once the bandit has commited himself into a dive to attack you, pull up into him and point right at him. Take a front gun shot if able. Point at him to deny him any lateral turning room. Hold your nose up climb until the bandit gets to about 2000-3000'. Then roll to put your lift vector in front of and below his flight path relative to the horizon and initiate a lead turn in the vertical. Do not fly out in front of the bandit...try to turn below his flight path. Use flaps if you have them. Make a max rate turn to align your fuselage with the bandit as he goes by you.
Once you have completed your turn, you now assess the bandit's position. If he is continuing in his dive, then go after him. If he is turning in the horizontal plane, then arc him. If he is 'booming' back up to altitude, then repeat this process over again.
Since the bandit has an energy advantage, you are playing a waiting game...waiting for him to make a BFM error that will allow you to get behind his wingline. Once there, you will have to use whatever energy you have to close in for the kill...or at the least, remain neutral.
Andy