Ok I get fuel at a shity place (i know bad idea) so i just get enough to get to the closest fuel station thats good (about 20 bucks) by the time i get there my truck seems to be idleing high at about 900 rpm then i notice the tranny acting funny. i come to a stop when i go the engine rev's then i let off the throttle and 1st engages. so i think bad fuel i imediatly go fill up with good fuel to try and dilute the bad. well now i am through a second full tank a new oil change trany spin on and doing the fuel filter tommarrow. what i noticed is it seems to only do it once or twice with in the first 15 min of driving then its gone until i shut the truck off. the truck has 191.000 on it maybe internal filter is cloged. i just dont see how the fuel filter would cause it to not engage 1st when cold. thanks