Why are channels pixilated & distorted?

I am still getting the same pixalation and freezing on all boxes

The pixalation and freezing is sporadic and intermittant, it wasn't happenning when the tech left but started up again later. No I can't screw on ot the boxes directly into the cable outlet. The way it's configured doesn't allow me to do that and it wouldn't tell me anything because of the sporadic nature of the problem For instance, it's not happening now but it could start later or it might be fine for a few days then start up again. One of the 3 techs I've had over the last month put filters on the outputs from the splitter, the next one took them off. The 3rd put a new amp on and changed some wires and the drop line. After each one left, it wasn't having the problem until later that night LAst night it did it about every 30 seconds with mainly screen freezing and brief sound outages.

Each time it happens, make a note of the weather. Temp, wind speed, and if it is raining, snowing, etc. If your internet is working, you can get temp and wind speeds for your area from weather.com or forecast.weather.gov  Then make notes of weather when there is no problem. If the problem seems to happen when it's colder, cold and windier, or raining, but not when it is warmer, less windy, not raining, etc.,  then there's prob addl outdoor wiring or connections that are bad which didn't get replaced.

Also, have the tech just install one wire splitter at the entrance. If there are any places with a splitter connected to another splitter down the line, that really weakens the signal. And since signal strength can vary from time to time, this could cause the signal to be bad only at certain times. I had a tech once who just replaced the line from pole to house, but left the other outdoor wiring on the house and ran a splitter off of another splitter. Had to have another tech come out and replace all the rest of the outdoor wiring on the house and remove the two splitters to replace wih one splitter to get the problem fixed.