98 Jeep grand cherokee engine knocking ?

I have a 98 Grand cherokee with the inline 6 engine, it has 160k miles on it and the car was taken care of pretty well. Has no rust, runs and drives extremely well compared to other cars iv driven..

There are problems tho with the engine i have noticed latetly and my mom keeps ignoring it but i think it might lead to something really expensive down the road..

The problems with the engine are when its running idle the engine makes a knocking noise, mainly comming from the driver side of the engine. The knocking is deff noticable when the car is cold started, after it warms up its pretty much gone, however it amplifies when next to a wall or another car which reflects the sound back.

When i go above 1200-1300 rpm the knocking pretty much goes away and you cant hear it anymore, when you let go of the gas and it drops to idle around 650rpm it shows up, and if you step on the gas while the RPM's go up the engine knocking follows the same speed.. Its not a ticking noise which the fuel injectors make.. This is a knocking.

Another thing i noticed is that after the engine is at normal operating temp around 200-210f and you turn it off for awhile like 5 minutes, and turn it back on.. Sometimes the engine RIGHT at the moment of it turning on (you know when a engine goes vroom and then settles down) you can hear a really nasty clanking sound. It sounds like 2 peices of metal hitting eachother. Then goes away after less then a second.

When driving the car runs really good, however ive only been driving for like a month since i just got my licencse. To me it seems like the engine doesnt have any power when going up hills. Not even large hills any slope that goes on forawhile the engine will seem like its having a hard time keeping up, and i really have to put my foot on the gas for it keep pace with traffic.

The engine does seem "fast" however like if you really pound the floor the thing will rev high and fly like a bird "for a suv lol" its just hills.. I dunno if thats normal or what.