I replaced the gaskets on the upper and lower intake manifold a few days ago. Upon completion the engine is making a strange squeel/squeek noise. I've removed the Serp. Belt and run the engine and the noise is still there so it'* nothing coming from the pulleys. What else should I consider. The noise was not there prior to the gasket replacement?

Check the PCV valve.

I did replace the PCV valve while doing the job. The old PCV valve was really nasty. Installed a new one....guess I can pull it back out and make sure it'* seated correctely.

Make sure there'* a rubber O ring.

Just today it started throwing the P0507 Code tho the idle is running beautifully.....but, alas, I tried to take the oil filler cap off and it would barely come off....when it did, it had a huge sucking sound.......so, I'm headed to change into the dirty clothes again, and start at the PCV....I'm thinking of just cleaning off the old one, putting it back in and see what happens. Thanks for your help.

WA-LA............guess what...when I pulled the new PCV out...it had no O-Ring on it! In my haste I just didn't notice. Seems like the new one would have come with required O-Ring....well put the an O-ring from my collection of many...and wa-la.....purring like a kitten...no noise no P0507 Code! Thanks again...amazing what trouble a .25 part will cause.