BAS ESP error comes on and it only does it after about 2-5 minutes of driving, and stays on until the motor is restarted.. What can i do to fix this?
the car only has 150k miles on it, is this when the car starts to fall apart?

 

It could be your brake stoplamp switch. There are MANY posts on this very subject. The DIY fix is also shown with pictures. Check it out.

At 150K miles on the clock... things will happen. Good luck.

 

and properly maintained it still has a lot of life in it.
Brake switch per above
diy on www.benzworld.org w210 diy section.
also check your contacts in the brake bulb sockets
and last but not least a weak battery on its last legs can throw that warning and it clears on restart because the alternator has brought the charge up to a sufficient level.
So check the battery,multi meter or any autozone etc or battery shop will check the output and charge.
Good luck and don't give up on it at 150k
I just delivered a 190k 91 300E that delivered 22mpg and had me cruzin for hours on end at speeds up to 138mph without missing a beat.
ohlord