Would this be the main pulley - as in the pulley on the water pump that is loose? If yes, then the water pump bearing is worn / faulty - and the water pump must be replaced.
Try the many on-line auto parts sources, such as; www.RockAuto.com or www.autopartswarehouse.com for the replacement parts. For example, they (Rock Auto) list the water pump for around $ 32.00, and they list the alternator for around $111.00 for your vehicle.

Possible Causes of Engine Hesitation or Stumble:

Dirty fuel injectors (cleaning the injectors often fixes this).
Dirty / clogged air filter element (change the air 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

Sounds like dirt or debris inside the defrost vents near the base of the windshield. Simple to clean - use vacuum. Difficult to access the area - unfortunately.
Steps to clean the vents;
Mix a solution of warm water and detergent in a bucket. You can use dish detergent or a small amount of laundry detergent to clean your vents. Choose one with a smell that is appealing to you.

Pry the vent covers off of the car using the flat-head screwdriver. Carefully insert the tip of the screwdriver in between the seam of the vent and the dashboard. Using leverage, push the screwdriver into the seam and pry the vent cover off. It should simply pop-off with the right pressure.
Drop each vent cover into the soapy water bucket to let it soak while you clean out the vent. Wet a soft cloth in the bucket and wring out any excess water. Wipe the inside of each vent generously with the wet cloth. Scrub off anything sticky or stuck to the plastic. Clean inside of the vents as far as you can get your hand. Be sure to wipe the top of the vents as well.
Dry the vents out using the second soft cloth. Wipe inside of the vents, inspecting for anything you've missed.
Retrieve the vent covers from the soapy bucket. Wet the toothbrush in the bucket and use it to clean in between the slits in the covers. Be sure to remove any grime in the corners of the vent covers.
Dry the vent covers with the dry soft cloth. Allow them to finish air drying if you cannot get in between the slots.
Snap the vent covers back into place. Line up the outside of the vent with the seams on the dash and push it into place until you hear it snap.
Spray out any hard-to-reach vents using the can of compressed air. The defrosting vents by the windshield are especially hard to reach and remove.
Use the wet, soapy cloth to wipe the top of the vent covers that are hard to reach. Dry the top of the vent cover using the dry cloth. Allow the vents to finish air drying.

You have to remove the intake manifold.

Compare the starters to make sure they are identical.

My initial questions are why were you replacing the starter and where did you purchase the replacement? Not all replacement starters are created equal!