whats the TPS pls

[STILL TRYING]

I was told there is a voltage from the TPS that could need changing to help inprove fuel economy,
Where is the TPS and what does it do?
How do you change voltage pls.
Also does the lift pump affect fuel , my engine is harder to start now than when I first got it, takes a lot longer to fire, yes plugs have been changed and diagnisis done.

[fairdeal]

you can get some helpful advice here

(apparently you've already received some which is not)

but you should start by providing the full model number of your engine

perhaps elaborate on exactly what "diagnosis" has been done, and by whom

we know you have Electronic Fuel Injection
with a Throttle Position Sensor
to tell the engine "computer" how open the throttle is

the TPS needs to be set to a precise specification - provided in the Service Manual

the lift pump certainly has an effect on whether or not there is fuel in the engine

[rodbolt17]

there are carbureted motors that alo used a TPS.
all the TPS does is give the ECU information on throttle opening angle.