Thanks for posting the code and data. You'll think I'm never satisfied but your code is just too long and complicated for me to follow. If you can, posting a minimal working example is what is needed.
For example, to import the data, shift the horizontal values in increments of 30, and plotting the result can be done in far fewer steps:
d = ConstantArray[0, 8];
Do[d[[i]] = Import["data" <> ToString[i] <> " " <> ToString[i] <> "0 Torr.CSV"];
d[[i, All, 1]] = d[[i, All, 1]] + 30 (i - 1), {i, 1, 8}]
ListPlot[Flatten[d, 1], Joined -> True, PlotRange -> All]
