Almost defo fuel related, as said do check the TPS you can actually test quite easy with a meter, an assistant may come in handy. Simply measure the voltage at pins 11 and 17. At WOT the voltage should be around 0.6V increasing with less throttle. At no throttle at all on PF01 they it will be open circuit as there is a switch built into TPS.

4x4 PF09 is total opposite of the above and doesn't have a switch.

Check MAP as well.

Martin