02 mustang gt oil pressure drops while in gear.

Today I noticed that it was bucking and whenever I would stop and put it in gear( RPM Would drop to about 550-600 as usual) and my oil pressure gauge would drop all the way down, but the moment I put it in park and the rpms raise, the oil pressure comes up. So I’m pretty certain it’s not a sending unitim fearing that my oil pressure is dropping below the threshold of the dummy gauge therefore causing it to read low ( 6-7 psi?)i’m kind of thinking that my engine has about had it. What do you guys think?