High pitch noise from engine

I just installed an used engine, in my '97 Aurora. After about 30 cranks, I got it started. But I am getting a high pitch noise that want stop. I thought it was the AC compressor, because I accidentally lost my feon, while taking the old engine out. I pulled the AC fuse and the plug at the compressor. But the noise didn't go away. I read the post by Zimaad, from Jan. and Feb. He thought it was his intake Manifold. He never said if he solved his problem or not. In the mean time, I am going to retorque my manifold bolts, and see what happens. I am also getting a "change oil now" in the information console. evidently the computer thinks the same old engine is still in the car. The guy that sold me the engine told me he had cranked it up, and that there were no problems. Although he took the throttle body and a few other things off.

Okay I reset the "change oil now" in the infomation center. I got that solution from a previous post.

Okay problem solved, it was the intake manifold bolts. I over torqued one manifold and cracked it(I had a spare). So I did it by feel, tightening them a little at the time. Untill I I was satisfied they were tight enough. I figured I could always wait untill the engine was cool(as stated by the manual), and tighten them some more.

Glad it all worked out for ya.