No need to reply, but your comment concerning the cold air intake reminded me of a similar problem I had. I didn't call it a squeal, but more of a whistle, beginning when the engine was hot and the Outside Air Temp was cool and developing over time to whistling anytime the engine was at idle (the intake manifold pressure at it's lowest). I'll not get into the whole troubleshooting process, but the root cause was a loosening of the 4 rearmost intake/exhaust manifold bolts, allowing air to be sucked past the gasket into the intake manifold and whistling. In my case, by the time I figured it out, the damage had been done and I ended up replacing the exhaust manifold and the gaskets. As things go, it turns out I could have salvaged the exhaust manifold but for time constraints, I shotgunned the repair. Later, when I had the time, I took the old manifold to get it resurfaced at a local shop (successful, by the way), and the owner told me that this was common on in-line 6's, especially after replacing the gasket. The newly torqued 4 rearmost bolts work loose with temperature cycles and need to be re-torqued several times. For me, after a week, I re-torqued the bolts, waited two weeks, re-torqued, then after another month, re-torqued them again. Each time, I could detect that tightening was happening. After another 3 months, I could not feel any further "working loose", except the very FRONT bolt took some tightening. But, my whistling problem was fixed. I've become very proficient in getting a socket onto and re-torquing these bolts without climbing underneath the Jeep!