Strange intermittent touchscreen behaviour after swapping

[alban]

Hello All
Running OmniROM 4.4.4 TWRP 2.8.? Unrooted
Dropped tab and replaced broken digitiser and lcd with whole screen caboodle from my old bricked ME301T.
Now get problems with screen - fails to register touch then flies over screen etc. Unusable. Hardware glitch I thought. Checked all connectors - all good AFAIK.
BUT odd thing is that it cleared up and behaved normally for a time after
1. Hooking up to usb PC connection to activate Helium x2 - but cannot replicate consistently
2. Reset from TWRP. Works well! But not every time.
BUT as soon as it went to sleep and rewoke the old problem resurfaced. Same for reboot.

So is this hardware as it fixes itself in certain circs? What about going to sleep will cause problem to recur?
Thanks.

Edit: OK so read around... looks like I may have to reflash touchscreen firmware and need to be on stock 4.2.1 ROM to do this apparently. http://forum.xda-developers.com/show....php?t=2631698
So will do that using correct Asus firmware and Install option in TWRP? However as I'm on OmniROM will that cause probs as I don't have the stock apps installed?
If 'easy' method doesn't work unsure which touch firmware to go for to try with adb...

[janner43]

You didn't post this here in error. It was moved to this section as you are running non-stock firmware and have replaced the hardware as well.

Please do not cross post this thread again. The other copy has been deleted. Thank you.

[alban]

Apologies!
OK so I've tried to install correct stock Asus firmware via TWRP. (Was on 4.2.1 originally). TWRP reported successful but got stuck in perpetual bubbles on restart. Also tried SD card install from RCK several times following the Guide - no luck.Looked like it had worked as got a progress bar but it went v slowly then rebooted but still bubbles and dead robot... Is this due to not having stock apps installed?
Wrong SKU? - shows WW on bootloader startup now but I realise I didn't check beforehand just assumed as in UK it was WW.
I can use Fastboot a bit but a novice. Device is recognised by it.

Edit:
Using Linux Mint 17.3 opened terminal in folder where blob was
Tried fastboot flash staging blob All seems to work OK. Get prog bar behaving in same way as with SD card method then bubbles on reboot...
then tried
fastboot -i 0x0B05 flash system blob Get bar etc etc Repeated, same result.

Edit: Used 'fastboot erase userdata' then flashed system blob - worked! Now back to Stock 4.2.1.
Still got touchscreen issues tho...

Edit: Partly solved by this http://forum.xda-developers.com/show....php?t=2631698 as above