I got my XLE V6 brand new in the spring of '98, it's been very good to me ever since. Had to replace the tranny twice a few years ago as well as a few other odds and ends, but 420km later it still runs very well. Body is in good shape considering the winters in Ontario. Lately, it has started to develop a weird momentary loss of power at cruising speeds.

The best way to describe it is like the wheels are losing grip on short patch of ice. I first noticed it a few months ago and ignored it until recently when it seems to be getting worse. In the beginning it was barely noticeable but now it's getting more pronounced and happening more often. It is very brief, just a fraction of a second. It happens on dry roads and always above 80km/h when the transmission is in the top gear. The RPM barely registers it but I've seen it dropping briefly. There are no malfunction lights coming on and everything is back to normal after that. There is no pattern of when it happens, I can go for 10+ minutes between them or I might get 2 or more in the span of less than a minute. Clearly something is giving way. I suspect the clutch in the torque converter, but this is a wild guess on my part.

Any ideas? I have an ODBC II scan tool but not sure what to look for.

 

If you have an ODBII scanner that can read Toyota codes check for pending codes.

The trans has RPM sensors. Not sure if the scanner can read these but it so can determine if the trans RPM is dropping when the problem happens.

When this problem happens have you tried more throttle to determine if the RPM rises but the cars does not accelerate as in slipping?

Look for a trans a torque converter lockout switch on the gear selector arm or there is a button. One switch changes the shift pattern and the other locks out the converter. The converter locks up in high gear when engine warm and MPH about say 40ish. Lockout the converter and determine if the problem still happens.

How is the trans fluid condition and level?

 

I replaced the fluid about 33,000km ago (almost 2 years) but I might have overfilled it.

My ODB2 scanner is not reporting any pending codes.

I cannot really throttle it when the power loss happens because it is very, very brief, I would say less than half a second. I don't even have time to look the the RPM gauge.

All I have on the gear selector arm is the O/D switch. I don't know where the converter lock-out switch is located.

 

O/D switch is the lockout switch.