Buzzing noise in my 1996 Ranger engine!

[strangerdangeranger]

I've had my '96 Ranger less than two years and there is a periodic buzzing sound coming from the engine compartment.

Up until a few weeks ago, the noise would only occur once every few months. Now it happens several times a day for about 45 seconds or so.
If it happens at a red light, just before it stops, the pitch of the buzzing increases and when it does stop (with my foot on the brake), the engine suddenly drops from about 1000 rpms at idle to about 500-600 rpms and it feels as if the truck is about to stall (it doesn't, however).

I'd hate to bring this somewhere and get charged big money if it's something simple that I could fix on my own.

Thanks,

Jack

'96 Ranger, Auto, 4.0l, 4wd, 72k

 

[killj0y]

If it happens at a stop drive it, then get off and search for it and/or try to record it. Any codes?

 

[Earl43P]

Idle Air Control, or IAC.

You can disconnect its electrical connector and see if buzzing goes away.

 

[the_gunslinger]

^^ there was my suggestion as well.