96 Monte *RPMs drop while driving*

I have a 96 monte carlo ls 3.1. Is idles rough but the shop I took it to left the idle rpms at around 700. I dont know if that is too low or what but I cant figure it out. When Im driving down the road and get into 3rd gear, the rpms drop down about 500 and the car sits at that speed unless I let up on the accelerator, then it jumps back up to where it is supposed to be. Anyone know what could be causing this?

I recently had the egr gasket replaced, the intake manifold gasket replaced, the serpentine belt and tensioner replaced, and had a full tune up and oil change. Just cant figure this car out!!!

yes. It's normal. what it appears that you're noticing is the torque converter "locking." This creates a no-slip connection between the engine and the automatic transmission while in high gear, which drops the RPM's and allows for better gas mileage. When you take your foot off the gas, this action disengages, or your engine would stall when you slow down too much or approach a stop sign.

i have a 95 monte carlo and mine will act like it wants to die win i try to stope to quick. and my low track dosnt come on but i will give it a little gas and it will burn out thats not right is it

Try looking into (IAC) Idle air controle motor
If

Try looking into (IAC) Idle air controle motor
If the check engine light is on