I have a 00 f150 5.4L V8. i just hit 90000. Over the last 2000 miles a weird noise has occured. When I start the truck it makes a noise coming from the front passenger side of the engine bay. it goes away after about 1 minute or until i drive off an reach about 2000 RPM. you dont hear it while driving just when the trucks been sitting and I go to start it. the noise it makes kind of souds like a diesel truck.. I went to 3 exhaust shops and got 3 different answers from them. 1 said it was manifold gasket, 1 said it was the cat, and the other said it was a lifter.. Im running out of ideas of how to pinpoint this noise...anybody run into this problem or have any encite as to what to do?

 

What do you use for oil and filter? Weight and brands, please.