C280 Fuel Pump
 

I have a very intermittent problem with my 1995 C280. Occasionally when coasting along (usually about 40 mph), the fuel supply will totally cut off for a second, then go back on, and then cut off again for another second.
Also, occasionally when I gun it from a stop, it will go a little, the lag for a brief second, and then go again.

Benzmac told me that the fuel pump relay was not a common problem for the C280, but that the fuel pump itself is what usually fails. I now have 101,000 miles on my car. Fuel pump has never been replaced. This might not be the cause of my 2 small problems. When the fuel pump fails, is it gradual? Or does it usually just happen instantly with no warning signs? Would it be worth it to bite the bullet and buy a new one from FastLane ($177)? It might be the cause of 2 of my problems, but if the average life of the fuel pump (so I've heard?) for my car is about 110,000 miles, would it be smart to just replace it anyway as preventative maintenance? What do you think?

Also, how involved is it to change the pump myself? Is it in the engine bay or back by the gas tank and the fuel filter? THANKS A BUNCH!!!!