^^ All the vigos that used to come to my shop - they had their original fuel filters from Toyota motors - after 45,000 kms - that is a sure way of saying BYE BYE to the fuel system.
The other factor was the stupid interheater on the engine - and lastly the MAF dying causing good startup but running problems.
I used to treat them to liqui moly purge too - it can really clean out the system.