I have a Samsung DLP hl-s6187wx/xaa from 2007 and just started having picture issues the day I installed Frontier's FiOS into

Sorry I see my info was placed in title, thus my information was missing!
I had no previous problems with my Samsung DLP when connected to FIOS 2 yes ago or Bright House a week ago. So I needed faster upload and went back to FIOS, but now they dropped a fiber-optic cable too. The STB is a Motorola QIP 7232-2. When connected with New HDMI cable picture scrambled but clear sound. We tried RBG cables ( from what I've read this works) to no avail. The cable guy from Frontier tried going into Motorola's secret menu to set 4:3 picture on/off to no avail and he tried various settings from 420i-1080p...still no luck. Then like clock work after 30 min. The picture was clear.
So he waited and checked lines and other stuff associated with their end. After about 1 hr. we turned Tv back on... screen scrambled. I forgot to include...if the TV is NOT in 'game mode' no picture at all. ( I didn't check if after 30 min if it was viewable as well). When in 'Game' mode you can make out somewhat a picture that's scrambled. ( Mainly white horizontal shifts with a green horizontal bar about 1-2" running across the bottom.
He left said tv too old. I pursued Samsung next and explained same story...tech said TV too old.
So my question is if it's so old why after 30 min. my picture is clear? Previously I did replace the bulb and color wheel with OEM parts, reset counter and everything ran smoothly on Bright House and PS4.
Thank you, for your help.