RPM Drop while accelerating

Hopefully someone can help me out with this: I have a 95 lumina 3.1 and recently I've noticed that when accelerating normally, the car seems to bog down and the RPMs drop from around 2000 to 1500. If i take my foot off the gas and then press it down again, the car will accelerate, but when it gets to that range it drops again. It especially happens when the car is cold and whether I am in overdrive or regular drive. Has anyone had this happen to them too?

Hopefully someone can help me out with this: I have a 95 lumina 3.1 and recently I've noticed that when accelerating normally, the car seems to bog down and the RPMs drop from around 2000 to 1500. If i take my foot off the gas and then press it down again, the car will accelerate, but when it gets to that range it drops again. It especially happens when the car is cold and whether I am in overdrive or regular drive. Has anyone had this happen to them too?

if this is true when cold it can be vacuum leak start here first.