[Juliano]

Tachometer revs up intermittently when the car feels like changing gears or feels sluggish when trying to change gears.  Can go an entire trip with no issues or can go an entire trip with issues.  Sluggish usually on lower gear changes and revs up to 3500 on highest gear change.

Diagnostic is showing no faults
Economy has dropped a Litre
Car has 120000kms on the clock

I have changed the fuel filter, valve gasket, spark plugs, battery, timing belt

I originally thought it may be a timing issue but now wondering if it could be a fuel/air mix issue

Now thinking what the problem could be as I am obviously catching it before the engine realises it has an issue

Possible
Injector o-rings
CPS
Throttle body sensor
Oil control Valve Timing Solenoid
Hopefully not a cracked piston

Anyone got some more ideas to work off or has had a similar issue.

[tw2005]

Auto?

[tw2005]

Got my glasses on, So it's AUTO? Sure it's not a trans issue? Are we talking like shift flare, it goes to change but instead the RPMs go up or what? How long you had it now? From New?

[Dazzler]

I'm with tw (Gerard) I immediately thought it sounded like the torque converter slipping. 

[Juliano]

Thanks. Automatic. From new condition.

Sounds right. Shift flare or slipping.  I'll change the transmission fluid and filter and hope to not find anything shiny in the tray. If all looks good, I'll put some seal fluid in to rejuvenate the seals.
If that doesn't work, then start scratching at ideas again.

[Dazzler]

Thanks. Automatic. From new condition.

Sounds right. Shift flare or slipping.  I'll change the transmission fluid and filter and hope to not find anything shiny in the tray. If all looks good, I'll put some seal fluid in to rejuvenate the seals.
If that doesn't work, then start scratching at ideas again.

Good luck with it. You are one up on me. I am D.I.Y. but wouldn't tackle that. 

[tw2005]

Thanks. Automatic. From new condition.

Sounds right. Shift flare or slipping.  I'll change the transmission fluid and filter and hope to not find anything shiny in the tray. If all looks good, I'll put some seal fluid in to rejuvenate the seals.
If that doesn't work, then start scratching at ideas again.

Maybe it would be better to get a proper diagnosis. These boxes are known to have Valve Body wear issues so it could be that and the valves are sticking and or excessive wear meaning pressures won't be correct.

There's no gasket on the Pan so be prepared for that, personally I'd reseal using liquid sealant like Three Bond 1281

120000k is peanuts for the box if it's been looked after but if it's the original fluid then i'm thinking it's too late.

If changing, flush it out , don't just drain and fill.

I would not try any magic additives, I think you will be wasting time and money.

SPIII is the fluid, i've used penrite multi FS but you could try a Mitsubishi dealer for 5L bottles of SP3 and be cheaper than the 4L bottles of multi you can get.

A VB from korea is about $900 landed and it can be replaced in car , removing the pan and filter .

I have read  of faulty Harnesses too but not here in this forum yet.

If the vehicle is city stop start i'd flush trans every 60000K

[nzenigma]

Juliano, Im not sure about your driving experience so don't want to rubbish you.
Tw is probably correct, but transmission flare is pretty obvious , so Im curious that you have done a lot of work on the motor.
Maybe a mechanic should take it for a drive before we go off half cocked.

[Dazzler]

Juliano, Im not sure about your driving experience so don't want to rubbish you.
Tw is probably correct, but transmission flare is pretty obvious , so Im curious that you have done a lot of work on the motor.
Maybe a mechanic should take it for a drive before we go off half cocked.