Whenever I would flush the toilet it would come up through the drain in the bathtub but then would go back out again. As long as it was going back out I choose to ignore it. But then I started having problems with my kitchen drain not draining so I put liquid plumber down the drain when that didn't help I dumped other products to unclog it even ran a snake through it with no avail. I also changed all the pipes plus vent under the sink. Also when I snaked out the kitchen sink my problem in the bathroom cleared up. The water doesn't gurgle back up into the tub when I flush. This problem has me completely baffled. Hope someone can solve it for me. Also I live in a mobile home

As a repair plumber I have never recommended using harsh chemicals. In your drainage system. Besides they only seem to work in TV commercials and when you try to remove the water you could burn your hands or damage your eyes.
Having said that, when you snaked the kitchen where did you snake from? The roof vent or did you remove the and snake from there? Back to you, Tom