The check engine light is located on the dash and stays on if the computerized engine control system detects an engine performance or emissions problem.

First step - have the check engine light or stored fault codes scanned - for free - at any local auto parts store; Advance Auto, Auto Zone, NAPA. Then, post a reply as 'add answer' for more assistance.

If the new battery is going dead,yes it could be the alternator or regulator.Something affecting the charging rate.When a new battery is installed the charging rate should always be checked at the same time but most people don't do that if the battery is installed at home.Another thing is a short drain in the system.Check drive-belt tension,inspect alternator wiring harness and the connector,check fusible link if it has one( located between starter solenoid and alternator) I suggest you get a Subaru repair manual for your model so you will know what applies to your vehicle.

The check engine light is located on the dash and stays on if the computerized engine control system detects an engine performance or emissions problem. There are literally hundreds of possible fault codes.

First step - have the check engine light or stored fault codes scanned - for free - at any local auto parts store; Advance Auto, Auto Zone, NAPA. Then, post a reply as 'add answer' with the specific code for more assistance.

All vehicles manufactured after Jan 2003 have a program built into the vehicles electronics that stores excessive road speed data. When a vehicle reaches and exceeds105 mph, a data file is stored within the vehicle computer that then is uploaded to local law enforcement computers the next time the vehicle is plugged into the smog station's computer when your vehicle gets it's annual inspection.
I am just jokin' around. maybe got ya for a second though..
Buy a code reader at amazon for $25 and plug the reader into the diagnostic connector under the dash and read the fault codes. Update the post with code numbers and I can assist you with a fix for your car.

Okay, the code is: P0244

P0244 = Turbo Wastegate input error solenoid 'A' Range Performance.
Basically you are overboosting. Are you watching your boost? The stock wastegates tend to overboost in cold conditions and especially in higher gears, just ease off the throttle a bit. Possibly the issue is related to a solenoid malfunction. This is located in the front of the Intake Manifold by the altenator on your model.

As a first step - verify the wastegate solenoids operation. I suspect it's probably sticking at times or it could be an electrical issue. You'll probably want to buy a Subaru WRX repair manual or borrow one from the public library. Find out what wires are what, where the solenoid is located, etc. Go from there. Verify all wiring & connectors leading to the solenoid. Try applying voltage directly to the solenoid to see if it's working correctly or not.

Replace the wastegate control solenoid valve

What sounds more wierd to me is someone that is going to replace contacts inside of a starter. Starter motor is like $150 to $175 give or take (at a shop with some markup on the parts) for the part without labor. I agree that your cause is a bad starter. What are they billing you for this procedure for parts and labor and will they guarantee that there changing of contacts only will solve your problem and will they warranty the starter to be free from faults again for at least 1 year? Most replacement starters come with a one year warranty, sometimes more. That is why I question whether replacing contacts only is a good idea.

More than likely - either or both components can cause the hesitation issue. Try the many on-line auto parts sources, such as; www.autopartswarehouse.com, www.rockauto.com - to list only two. They (RockAuto) list the replacement mass air flow sensor from around $103.00 and the O2 sensor (downstream) from around $44.00, and the upstream O2 sensor from around $111.00 for your vehicle.

Could be as simple as dirty fuel injectors Could be transmission related because of hill comment. The vehicle has a few miles on it and unless you recieved maint. records you are really having to start your preventive maint. from scratch. Change oil and filter, spark plugs, air cleaner filter if looks dirty, use some fuel injector cleaner and check transmission fluid, front axle boots for damage, etc. No magic here, just a few tips. Hope it helps.

First step - have the check engine light or stored fault codes scanned - for free - at any local auto parts store; Advance Auto, Auto Zone, NAPA. Then, post a reply as 'add answer' for more assistance.

Possible Causes of Engine Hesitation or Stumble:

Dirty fuel injectors (cleaning the injectors often fixes this)
Dirty air filter (change filter)
Dirty / clogged fuel filter (change filter)
Bad MAP (manifold absolute pressure) sensor
Bad TPS (throttle position) sensor
Bad or dirty MAF (mass airflow) sensor
Low fuel pressure (leaky fuel pressure regulator or weak fuel pump)
Vacuum leaks (intake manifold, vacuum hoses, throttle body, EGR valve)
Bad gasoline (fuel contaminated with water or too much alcohol)

Sometimes, what feels like a hesitation is actually ignition misfire rather than lean misfire. The causes of ignition misfire may include:

Dirty or worn spark plugs
Bad plug wires
Weak ignition coil
Wet plug wires

No - the cruise control will only disengage with action from the gas or brake pedals. Won't hurt anything.

OK - need more information. Is there any question or issue regarding the engine or spark plug wires?