Turn Signal starts normal slows fast

Is my turn signal switch toast or is this a deeper problem.

Increase your idle to 1000 rpms see if it still lags.

Your alt pulley could be the wrong diameter.

I'll try it tommorow

as said if it's not a low voltage at idle problem R&R the flasher can

missed the beginnings. my bad.

Sounds like a flasher problem, to me