So to make sure I'm clear, everything was fine and you got a plow kit. You test fitted the plow, raised it up and what not, and then took it back off. After that, your symptoms started. Sound right?
Did you do any other work/maintenance to it between the plow test and now? Did you have any issues with the plow test?
The reason I ask is, it sounds like you've got a problem with your brakes or something rubbing up front. If it's pulling and dogging, but otherwise running ok (not missing), I'd wonder if maybe something got bent and it interferes intermittently, or else maybe something was left loose after removing the plow.
Could you have had an accident of sorts while test fitting the plow? Maybe you lost your grip and it slipped, that sort of thing? Any sort of damage to the front from the testing is what I'm getting at.
Or is the
Engine running ragged and you think the problem is there? Could you be intermittently blocking the intake in some way somehow? Air filter clean?
I'd start by inspecting the mounting points of the plow, and all around the front end. Look for wear/rubbing. If it's got disk brakes, look to see if one disk is discolored way more than the others.
Interesting issue