Loss of power...can't pinpoint why?

[VX KAT]

IIRC, the consensus was that if you have an older, un-maintained tranny, you should still change the fluid & filter but you should NOT flush it. Should probably stick with standard fluid rather than synthetic as well.

I thought that whole issue was only referring to the engine oil, not the tranny...???? Some say don't switch over to synthetic motor oil later in the engine's life as it's detergents may clean the varnish and other crude a little too well and leaks may be uncovered when the crude plugging the hole is removed.

I might have somehow missed the commentary about the tranny though....??

[Y33TREKker]

I thought that whole issue was only referring to the engine oil, not the tranny...???? Some say don't switch over to synthetic motor oil later in the engine's life as it's detergents may clean the varnish and other crude a little too well and leaks may be uncovered when the crude plugging the hole is removed.

Agreed. That theory has always been associated more with engines and switching from conventional to synthetic oil as far as I know.

I personally think it's just the opposite with transmissions. If the service history is unknown on a trans, the best thing a person could do is go ahead and change the fluid and filter. Going the extra step of flushing a trans has always been debatable, but if I was going to try it, I'd personally go the Seafoam route (drain an equal amount of trans fluid, add the Seafoam, circulate it for awhile, then drain everything and replace with all new fluid).

As far as you CEL's, if you already have some specific emission/exhaust codes, you could also always swap your current O2 sensors around and see if the code(s) follows the sensors. Given the mileage you've stated, if they've never been changed, a faulty O2 sensors could also be the possible culprit, but if the loss of power problem started occurring after the spark plugs were changed, it's also possible that the plugs that got installed weren't cross-referenced correctly and the ones that were put in aren't the correct heat range.