Help in placing "2 parboxes in a single Row" in Bulleted or numbered Items

The paracol package might be a good option for you.

I made a simple list that looks like your layout using enumitem. You need to remove the skips above and below the list to get equations to line up easily, but you can fiddle around with things depending on your exact set up.

documentclass{article}

usepackage{microtype}
usepackage{lipsum}
usepackage{paracol}
usepackage{enumitem}

newlist{step}{enumerate}{1}
setlist[step]{
  label=Step arabic*., resume, leftmargin=5em, topsep=0pt, partopsep=0pt,
  after=vspace{2ex plus 1ex minus 0.5ex}
}

columnratio{0.6}

begin{document}

begin{paracol}{2}

begin{step}
item lipsum[2]
end{step}

switchcolumn

noindent
begin{equation}
  x = y
end{equation}

switchcolumn*

begin{step}
item lipsum[2]
end{step}

switchcolumn

noindent
begin{equation}
  x = y
end{equation}

end{paracol}

end{document}