hello all...I have a problem has me stumped. I've got a well used 305 in my truck that is making a grinding noise at idle only, putting it in gear makes the noise worse as it lowers the RPM's, turning on the AC makes it even worse. With any these conditions once the RPM's crest roughly 1200 the noise completely goes away. I've tried using a homemade stethoscope to pinpoint the noise, but i can hear from the front of the oil pan to the transmission case behind the TC. The only other thing I have noticed is going down the road if I give it more gas to accelerate the oil pressure will drop and when I let off the gas the OP will jump back up 5-10 PSI. Thanks for any help ya'll can give me.