it runs like it's barely going to make it down the street?

I'm driving a 'Dodge Ram LE, 5.9, runs strong, always starts/shuts off easily but lately when driving for the first time(s) of the day it's running like a dirt bike that's "lugged down". If I give it full gas it runs but that's not o.k.; so it runs like it's barely going to make it down the street while sounding like a freakin tractor & a "lugged down" dirt bike. Sometimes it'll come out of it within just a few miles while driving my boyfriend just 5 miles to work, other times it doesn't wanna run right til I've started up again to go on my 2nd errand of the day. There have been a few days lately, when it's warm in the morning, that it's actually run perfect from the get-go but 6 outa 7 days it's SOOOO difficult to drive cuz it has NO UMPFF, can BARELY make it up the on-ramp!! Is this a fuel filter issue, which was suggested to me, or maybe the choke sensor?? My manual does not tell me how each sensor works &/or how the vehicle would run if so-n-so sensor was NOT working properly. I'm not able to ck each sensor and don't want to just start changing random parts. I don't have enough $$ to be that frivilous. Please help, I'd REALLY APPRECIATE your input. Thank you!!