In some places/states hunting with FMJ ammo is against the law.
Bullet placement beats velocity just about every time.
Have you tried the heavier .223 bullets?
Funny (not haha funny) that we send our soldiers and Marines out to fight armed enemy with a round that doesn't reliably put down a coyote.
I've never hunted coyotes, foxes, bobcats, etc. Just ground hogs. Head shots kill, right now. A little bit off, not so much. The .223, in the right rifle, with the right ammo and the right shooter is hard to beat as a varmint rifle.
I'll bet it's hard to get comfortable/accurate shooting out of a golf cart. Have you tried tacking the camo/cover down at an angle and moving around under it to engage the coyotes from a good sitting or prone firing position?
I read a story in Guns and Ammo many years ago. At that time one of the writers was Elmer Keith (I don't remember if he was the handgun editor or if Bob Milek had moved into that position by then.)
Elmer said that he a buddy used to try all kinds of different calibers/bullet types on the various varmints/animals they came across while out riding their horses around the country side. He say a 9MM FMJ round would not reliably put down their big western jack rabbits unless you made a good head shot. If shot through the body they would often jump/run some distance before collapsing.
They also got on a lathe and made a bunch of solid bronze bullets for a .220 Swift. I don't remember the bullet weight but those lightweight bullets had to be absolutely packing the mail when they left the muzzle. They were of course, non expanding when hitting and animal. When they shot jack rabbits in the head the rabbit died. When they shot them in the body the rabbit would pick it's hind leg up, scratch at the wound and then continue to eat awhile until it collapsed at some point. He decided from that, that even extremely high velocity alone wasn't enough without good bullet placement.
Having typed all that, coyote hunting with a pistol might be fun. Squirrel hunting with a .22 (Ruger Mk1 5.5" bull barrel) used to be a lot of fun for me.