truck wont idle!!
 

Yesterday my truck was running an idling fine but last nite something happened an my truck will not idle, it just dies. if i start it an give it some fuel it will stay runnin but i have to hold it and when i do it wont stay at a constant rpm it drops lower an then goes back up. idk wat it is, i checked my governor springs an everything else i can think off. any thoughts on this? thanks.

I might be sucking air if that's the case you could have a bad seal on the fuel filter maybe a craked fuel line somwhere I'd start with those 2 if not it could be the lft pump

yea i checked all my lines an changed the fuel filter today an its no better still. at high rpms (1500-4000) it runs fine but under that you can hold the throttle steady an it will drop rpms an then go back up or sometimes it might just stay lower. im thinkin lift pump maybe, hopefully, im gonna check it with a pressure gauge tomorrow.