I have a 2000 3.8L that when at idle you bump the throttle the plastic intake box on top of the intake manifold will change shape(looks like it puffs up) and makes a sound like air sucking in or blowing out it is hard to tell which. The motor will miss and cough from time to time and does not have the power it used to at one point it had codes that said left and right bank lean so I tried replacing the MAF sensor and the 2 upstream O2 sensors the check engine light stayed off for about 500 miles and it is back on now. I had autozone scan it and they had a code # 174 not sure what that means. I was wondering if anyone on this site had any ideas what would be up with the air intake could I have a blow by issue or a stuck valve. Also probably the most important part that I forgot is that air box has oil all over inside it and standing in the bottom. Any help would be greatly appreciated.