troutstew

I have a 91 pickup 4x4 with a 3.0 in it. I had the clutch replaced along with flywheel about a 2 months ago. All has been well(kinda) until two weeks ago during a long trip to the mountains. I noticed at idle it would drop down to 6-700 rpms and it will almost sound like it's camming. It would then hesitate on the first time or two you tried to accelerate but then run fine. It would also idle normally if you give some throttle for a few seconds and then let off.

Fast forward to tonight. First time I have driven it since the trip other than down the road a couple miles. It now drops to about 400 rpms during idle and has a much more distinct rpm bounce but doesn't really show on the rpm gauge. As I sat and let it idle while doing this I noticed a rattling sound from the transmission. Sounds somewhat like rocks rolling around. I can once again give it some gas and every once in a while make it go back to idling normal. The rattling sound goes away anytime the rpms are above 7-800 rpms.

Any idea of where to start? I am not very familiar with this truck or trucks in general other than fixing more obvious mechanical issues.

Thank you for any help