The TPS is the Throttle Posistion Sensor, its mounted on the right hand side of the carbs and has a clear/white-ish 3 pin connector just under the frame brace infront of the carbs.

If the bike is running stock jetting with any kind of air box mods or exhaust then you need to have a play with the jetting as this can cause simular probs as to what you are having on WOT. Im guessing the bike pulls fine as long as youre not on WOT
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If I have to take the carbs off once more...