I am stuck at this. I got leather jacket and a pistol. Pistol makes no damage and leather jacket doesnt give much protection. When the second battle starts Tyler shoots me dealing 10-15 damage, 50% of my HP. I got 4 stimpaks and 1 heal powder. I try run outta the house but the f'ing Tyler runs behind me all time and it goes up as everyone running around house.

I can't leave the quest, how am I supposed to complete this? Or is my savegame doomed?

Just dont get involved in the fight. There is no reason to.

But Tyler chases me with his gun, killing me.

But, I could actually escape the situation. By sleeping a day before the battle and left the map. It told me I completed the quest and recieved 1000xp. Well, no better armnament looted from Tyler but atleast I got free 1000xp thanks to glitch.

If you or your companions dont get involved in the fight, his gang wont attack you.
Just stay round the side of the building while Lara and Co. kill them,

I mean the second battle where we storm the house where Tyler is having a party. That I could evade by leaving the map after the storm-the-church, and the glitch made me 1000xp for doing the storm-Tylers-party even I didn't do it.

I am assuming you have a save from before the fight either go for a wander in the wastes and level up a few times or go to flick shop and kill him and loot his body you should get better amour and weaponry of him but make sure he dosen't die to close to the bed or you won't be able to find his corpse.

You're using the restoration Project, not plain vanilla FO2.

Might be a good idea to include that in future help requests - that entire map does not exist in vanilla Fo2.

I apologize my stupidity.

Updated signature to include information regarding versions, let's count that one as a newbie mistake.