I am 1400, how do I improve my positional play? My lichess puzzle rating (tactics) is around 2100, while my game rating is only around 1400, so I'm pretty sure that means my positional play is utterly trash. There aren't any positional puzzles out there, and when reviewing games, I'm utterly clueless on anything positional since I haven't the slightest idea on how to evaluate a position, and guides on positional play seem abstract to me. 

I get by in life by memorizing sicilian opening lines and copying how IMs and GMs develop their pieces, but this only gets me past the early middlegame, and I'm essentially locked out of playing any opening except the ones I've carefully reviewed, like the modern, sicilian, and english.

I was wondering if there was a systematic way like a routine or checklist to determine a better position and a good positional moves, or if it was all dependent on pattern recognition. In other words, help please!
Positional thinking is more abstract than tactics.  If there could be an algorithm for positional thinking then positional thinking would be like tactical thinking and not something else.  However, there are thinking steps like noticing weak squares.

I suggest starting with a pawn structure book.  Soltis' "Pawn Structure Chess" is a classic and the book that changed my game all those years ago.  I really like "Chess Structures - A grandmaster guide" by Mauricio Flores Rios as well.

I believe it is best to start with looking at isolani positions as positional considerations are clear there, As I recall both books start with isolani.  After that skip to the chapters with the structures you play and start trying out the ideas in your games.  

Think about what the ideal placement of your pieces would be in the position separate from how to get them there.  

These books may have unintended consequences.  After I read "Pawn Structure Chess" I switched from 1.e4 to 1.d4 because I was more likely to get isolani and hanging pawns structures and outplay my opponents who didn't know about these things.