Fix Intel 8700 UHD630 graphics blinking

I'm trying to convert a HP EliteDesk 800 G4 Small Form Factor PC into hackintosh. I've sorted out everything on this machine except the in-build UHD630 iGPU. Currently it shows as "Intel UHD Graphics 630 1536 MB" and works flawlessly until it blinks (screen goes completely dark and comes back). I've noticed this happening right after the sleep.

Another problem is in the display settings I can only see 1080P and 4k resolutions but intermediate 1440P etc resolutions are missing.

Configuration:

1. CPU: Intel i7 8700
2. Motherboard: Q370
3. OS: Mojave 10.14.6
4. Clover Plist: https://justpaste.it/6bpfl
5. Clover Plist configurations modified for GPU:
   1. Devices -> IntelGFX -> 0x59128086
   2. Graphics -> ig-platform-id -> 0x59120000
   3. SMBIOS -> 18,1

Kexts used (/Clover/EFI/../Other)

1. IntelMausi
2. Lilu
3. WhateverGreen
4. USBInjectAll
5. VirtualSmc
6. VoodooHDA

I'm following vanilla guide and wants to keep the patches to minimal to get this system working. I've seen the Hackintool Framebuffer patching on TonyMac but gave up after sometime due to its complexity. In last 10hours I've tried so many things and many plist configs from forums and nothing seems to fix the blinking problem. Any help to fix the problem is appreciated.