I'm having this same maddening problem. Weird thing is that my Hackintosh did not have this problem at first -- not for several days of use. What seemed (I emphasise seemed) to trigger it was dual-booting into Win10 and leaving that running for a couple of days before switching back to Mojave. I swear I did not change anything about Mojave after struggling my way to a stable system.
So for quite a while -- two weeks, maybe more -- I had no problem sleeping and waking the Hackintosh running Mojave. Everything working great.
Then one day, rebooted into Mojave after running Win10 a couple of days. After that, sleep now disables the machine. Mouse lagging, even video glitches (momentary black screens) and kernel_task eating 70-80% of CPU continuously.
I tried deleting the infamous plist file but sorry to report it has had no effect.
If I reboot, all is well. So basically, I've been rebooting every time I return to a sleeping Mojave. Machine is not usable with this lagginess. But sleep/wake was working perfectly just a few days ago! Could Win10 have changed something about my mobo or video card?