Well the o2 sensors were replace. Cleaned the MAF sensor. Its been fine. Today the light came on and got codes p0171 and p0174 systeam to lean in bank 1 and system to lean in bank 2. Thought maybe the cold since it was 8 degrees here. Whats the next step to check please help

 

The MAF cleaning was a 'possibilty'.. But chances are that the intake O rings are pulling in un-metered are causing your lean codes.. 'Common' for these engines.. Usually they leak cold, and as the engine heats can seal making a diagnosis a little harder if checking with smoke/propane ect.. Without testing for fuel trimsand freeze frame datato verify the leaks and when they occured for sure, I can only offer you the 'tip'.. I would have a hard look into the manifold seals....There's a TSB for this issue that covers your model.. TSB 04-17-4

 

My daughters 98 explorer with a soch engine it had the same codes andat cold idle itwas up and down. So I replaced the iac valve and cleared the codes. Two months now and they haven,t come back.