Rough Running; Max 1800 RPM PA28-140

[Galaxy]

So I have a new problem that I am not liking too much. I went out to take the plane around the patch (haven't been out there in about 6 months) and when I went to do my run-up, I got MAYBE 1800 RPM from the engine max and it runs rough as hell. It does this on both mags, so I didn't think it was a fouling issue, but I went ahead and removed and cleaned/reinstalled the plugs to no avail. I have heard some people mention that I could just have a bad plug and they should be changed anyway (they are pretty old, but "in good condition" as of the annual last year). So, should I bother replacing all the plugs (will probably do that anyway) or are the odds that I am looking at something else? I have also heard that a sticking valve could be to blame. I have about 800hrs on the engine and last compression numbers we all 76/80 or better. So...what say you guys?

 

[sourdough44]

 

[JimC]

 

[magman]

 

[PilotPete]

 

[Jim_M]

 

[DaveB]

 

[baron_beeza]

 

[magman]

 

[Mountain Pilot]