The ECU water temp sensor behind the head is the green one. The brown one is the
cold start injector time switch. The temp sensor is a thermistor, so basically pretty
reliable. The test is to check the resistance of the sensor and compare with the graph
in the service manual.
Kind of awkward to get at it though, so probably leave that one for later. If the car
started and drove OK from a cold start in winter, I'd hazard a guess that the sensor
is fine.
The TPS could be a suspect. The wiper on the carbon track spends the greater part
of its life jiggling around at low throttle openings. So it can become worn in the zone
that your hesitation occurs. You need to pull the plug and test the pins on the TPS
itself. This is one time that an analog multimeter is better, but a digital meter will
get there as well. You watch the reading while slowly and smoothly opening the throttle.
You are looking for the meter reading to slowly and smoothly change from a high to a
low value, or vice versa. If the reading has spikes or dropouts (jumps around) instead
of changing smoothly and continuously, then you need to find another TPS.
Fuel is a hard call... its a possible, but as you say, WOT at high rpm requires a lot
more fuel than just sedately accelerating away from a stop light. On the other hand,
beating on the car will stir up any sediment in the tank and possibly add a bit more
crud to an already partially clogged filter.
If the filter shows no signs of being changed since the car was built, whack a new one
in there and cut the old one open. If it packed with a brown paste then that will be
rust particles from the tank. In that case you should probably pull the tank and see how
the pump and in-tank filter are looking. But test the TPS first

Cheers... jondee86
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