1998 Plymouth Voyager knocking sound louder during idle ALS

Not like a misfire litelaly like something down in the front is loose or vibrationg the fuel pump made all the lights do away the check engine is back in I know there is a random miss in one of the cylnders but this almost seem like an exhaust rattle but it idles at 1/2of what it was before 10000 rmp if I step on the gas and brindg it up to that idle speed no noise driveng no noise only on stopped idle no gas given hot as loud even when in gear quiet on freway mileage is holding no it has never made this sound before and it is very diffrent than when the cam and seals were done it was fine no noise after seals and no change ex one door pl stopped working fuel pump and filter it when things changed lights all stopped and only check engine has come on is it possable something is not connected tight if I had to guess it is somewhere by the oil pan or just above sometimes it sounds like near a/c compressor? Still driving but if it is something that I would be doing more damage by driving un fixed I want to repair please advise 3 car places have said it is dying no mech has auctually took codes or examined just listen to running they all wast 100.00 even jbs who did the pump and they knew 1 day after there was noise that was not there when the fixed the pimp for 600.00
oil is clean 1/2 way to needing change 1500mi on oil clean no shine or metal no chunks smells new not dark or black nice new color and smell not using any or burning any no blow by ect