The roller hydraulic valve LIFTER is clattering which rides on the camshaft.
Does it sound like detonation(knocking,pinging,rattling) If so,I would test the knock sensor to see if its functioning correctly.A defective knock sensor could easily cause the noise you described.A leak in the vacuum hose connected to the map sensor can also cause pinging if the map sensor is reading incorrectly.If the problem is caused by a mechanical issue rather than a sensor,you could do a compression test to see if one cylinder is way down on psi.If it is then a valve problem could be the culprit.Have you removed the valve cover to see if a rocker arm is out of adjustment??I had a valve keeper pop off the spring once just leaving one keeper in place and it caused the valve retainer and spring to pop up a little which wouldn't allow the valve to close completely.Rare case I imagine.Have you checked the timing to make sure it hasn't overadvanced.A faulty balancer rubber ring can cause this.A clogged egr valve or tube can also cause detonation.You can also check for vacuum leaks
could have a fouled plug? the clattering just maybe that a loose valve. domestic motors aren't know for there longevity.. High octane gas is a waste unless you have a high compression motor.. sounds like you have two different issues here a bad head unit and a fouled plug or plugged fuel filter..
Running rough like a boat?
The timing chain/belt may off. That's the first thing I would check. Next is checking the valves themselves. See if they're damaged. 24 year old car. Valves can bend and lose their seal
this may be a cheap fix you can try it first before you go any farther go to your automotive store pick up 2 cans of upper cylinder lube read the can first use 1 can per tank it may take an other tank an other can try this first before take heads off
Just one valve clattering and I always put high octane gas. Does good when you just cruise. When you give it gas it clatters and motor jumps like it is missing.
