Help me identify this rock song?

I remember that it was a very fast rock,but it was around 7 or 8 minutes long,it had some kind of weird screaming vocals,that seemed very forced,like the guy was constipated.The song was made of 2 parts,the first one was faster,but the second one had a short,very fast and crazy solo.The two parts were separated by an interlude which was some 10 seconds long,and sounded like a scale being played with a middle-eastern kind of tone on an acoustic guitar.The song was very good,and I think it was from the late 80s,from the sound and style.