Ticking noise

hello, i have a 2002 Dodge ram 1500. i Bought the truck about a year ago from a small auto dealership. it has 118k on the motor..the truck has after market headers on it, including new pipes and muffler the rest of the way back. several months ago, the check engine light came on,i immediatey went to autozone and got them to hook up a diagnosis reader. it came back with a code about an exhaust leak pretty much. i didn't think anything about it and kept driving it. about a week ago, i noticed a very small ticking noise at idle, and when the motor is under load. i didn't look into that either. kept driving. then a couple days ago, the ticking got louder within an hour. i came straight home and popped the hood to listen. whenever you start the truck up, the ticking is very loud. it sounds like a pencil hitting a piece of paper repeatedly. now when i rev the motor up in park, the ticking goes away. as soon as the rpms go down, the ticking returns, loud, then after about 5 seconds it will go to a quiet tick. now if im driving it and i take off, the ticking returns very loud, and for instance if im going downhill, the rpms are still above idle, and it still ticks, but when i come to a stop, it goes back down to a slight tick.
I have a Jeep Cherokee that i take rock crawling, trail riding, and that sort, so im a little familiar with inline 6 Chrysler motors, not so much with v8 motors. i bought the truck to have a DD. i don't know if the ticking is coming from an exhaust leak? or what. the noise is coming from the driver side of the motor, around the header and valve cover. ive checked from cracks in the manifold, and i don't see any signs. to me, if there was a crack in the manifold, it would be a louder tick. by the way, the ticking noise seems to be in sync with the sounds of the exhaust. my jeep isn't built to be a DD, but im scared to drive the truck, because if it is a lifter, i don't want to mess it up more. if anyone could help me or give me advice on what it mght be, i am all ears. THANKS

Sounds more like an exhaust leak from the header/manifold area. The manifold/header is expanding with heat just enough to quiet it down at idle but under load you can hear it good. I would check for cracks, if you see a black trail anywhere then thats your problem. Headers require maintinence and the gaskets need to be replaced periodically. The dodge manifolds crack often and need to be replaced. If the manifolds arent cracked you can replace just the gaskets. My 05 has a small manifold crack and i have the same noises you do

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i will buy a new gasket and put it on and see what happens

that or lifter tick and lifter tick shouldnt hurt anything. mine ticks on start up

What motor is this? If it is the 4.7, then the cause may be the valve-seat backing out of the head. Well known defect. This causes extra slack in the valve-train, and a ticking noise. Soon followed by the rocker arm falling off. Look it up.

its the 5.2 318

Make sure your header bolts aren't broke or that they haven't backed themselves out.