Grand Am Lifter Noise

I have a 96 Grand Am with 3.1L. I have been having an intermittent sound like a noisy lifter. More than just a tick-tick.
I have changed oil & added Risolone and sound went away for a couple of
weeks, but then back again. This time it was on for an afternoon trip and performance bad toward end of trip. Check engine light came on. Cyl #1 Misfire & Excessive Transmission Slip codes set. Cylinders 2-6, no misfire.
Removed some oil & added Marvel Mystery Oil. Better. Ticking for about 5 minutes, then OK. Pretty consistent, though.
Change oil after a couple of weeks again and this time a qt of CD-2. Really great. No sound for 10 days. Yesterday though it came back when I stopped somewhere for a few minutes and started up again. Next few starts made noise, but went away after about 5 minutes. Then one time it stayed on for about 15 minutes and performance was bad - low power. Didn't seem to be missing though. No check engine light.
(1) Would noisy lifter cause performance problem?
(2) Anything else to try or check for?
(3) How much of a job to remove intake manifold & replace lifters? Anything to be careful of / adjust? Will bad lifter be obvious (cannot really tell by using a wood stick on various locations of engine where sound is coming from). OK to just replace bad lifter?
Thanks, Dave
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Trans code is probably a seperate issue that will need to be scanned by a trans capable scanner. Is the lifter noise from #1 cylinder? Or is the miss, again, a seperate issue from the noise. Check plug, wire, and injector for #1, make sure there is no coolant loss into the oil, common problem with the 3.1's. but you would probably have already noticed this. You may want to pull the valve cover where you have the lifter noise, but get a second opinion to verify it is a valve train noise, first. "Dave @cinci.rr.com>" <dpugh<removethis> wrote in message

misfire.
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sound
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