Fourinhand

Okay. Offical frustration.

My Altima's been a good car to me for the past eight years. Thing is, everything that could happen wrong has already happened at ONCE.

My headlights dim in and out when I'm driving her. Dim-bright-dim-extra bright-dim-dim-bright-extra bright.
Had the alternator replaced. Problem solved.

She idles roughly at stoplights.
Had 02 Sensors replaced. Problem solved.

She sputters and bucks during high speeds and cuts off at stop lights/slowing to a stop.
Had distributor cap, plugs, wires, fuel pump, wiring checked, new battery
installed, in addition to the 02 Sensors and the alternator all replaced.
Problem NOT solved.

What am I missing? I've taken it to four different diagnostic centers (PLUS the dealer, TWICE) and everything keeps checking out okay. I know she's tempermental... but I'm an intern. I can't afford all this! What can I do??