Hello all my name is: Mario. I have a 97 GTO MR. The car was sitting for about a year. I cleaned it up and took it for a drive and it began to rain so I turn on the wipers only to be greeted with slow moving wipers. Do I need a new motor? Or the mechanism is seized and needs to be serviced. Would appreciate any advise before tearing it apart. Thanks in advance.
Id first try cleaning the wiper blade as good as you can. My front wipers were moving slowly at some point but after cleaning them they are back to normal.
Thanks for the reply. It’s definitely worth a try. Will clay the windshield and clean the wipers …… fingers crossed 
Cleaning and polishing the windshield will help but you also need to clean the rubber on the wiper blades.
I use:
Meguiar’s Mirror Glaze Vinyl & Rubber Cleaner/Conditioner M4016
on all rubber surfaces.
sorry for the late add to this, but I have found with mine was low voltage/amperage. from my reading, a 120amp alternator will only put about half when idling. take into account aged wiring and connections the idle amp out put could be even lower. when the engineers design the car , amperage output was based on all new and OEM components. put an High Output in my 97 Camaro, and the headlights diming up and down when i was stopped went away. another thing to look for on low amperage is that the crankshaft pulley may have been replaced with smaller diameter. that’s what i found out on my 92 SL even after i put in a HO alternator. when the voltage is about 13+, wipers work normally. when it starts to dip to 12 or less, wipers move in slow motion when on max.