Belt squealing for ~5 seconds after start

Hey ya'll

More of a general diagnose/repair question.

After the car starts, there's a squealing sound from the engine, then after a little while, everything is normal.

Specifics:

- does not matter if it's a cold start, or if it's a start after the engine had been running for an hour, the belt squeal happens after it starts

- when the belt squeal happens, there's seemingly more load on the engine, the RPMs go lower than usual idle levels, and sometimes dies after the the RPMs go too low.

- Either i give press the gas pedal a bit after engine starts, or leaving it alone after starting, the squealing eventually stops (after ~5 seconds), and the idle RPM is at normal operating levels.

My guess is that one or more of my bearings on some pulley is shot. What do ya'll think?

2000 Toyota Sienna LE

1MZFE 3.0L engine

Thanks!

PS - Magically, the squealing has not happened for the last few starts.

Several possible causes:

-Belt is loose and needs tightening

-Or if auto-tensioner, then the tensioner might be failing

-Some device driven by the belt is starting to fail/seize

-Belt itself is just old and needs replacing

So, remove the belt and check the condition of the belt, and try spinning all the devices that belt drives, make sure they spin free and easy and with no play. Reinstall a good belt and make sure it's tensioned correctly.

Matt covered pretty much all the bases.

Whatever it is, it will need investigating, especially as it appears to be a belt drive interference engine and if it's the cam' belt idler(s), or tensioner(s), it could lead to belt failure and engine destruction.