1.8T's are slow wtf! the 1.8 20v are slow yeah tell me about it, you think the 1.8 in the mk4 is bad try it in a passat.
On saying that there not really that slow in even in the passat, well not around town, but once your on a fast road and want to accelerate passed someone there no good thats where the turbo comes in..
As time has moved on, and cars have got faster and more bhp i have noticed that every faster car i've had, theres come to a point where over taking became much harder as times gone on, the mk2 1.8 8v ran out of steam, then the vr6 started to have problems overtaking freaks and even my 1.8T 200 bhp ish is feeling the heat trying to get passed crap diesels.
Get the fault codes checked, if the mil light doesn't turn on and off at engine start because the early golfs don't have the management light activation, and so there could be fault codes stored but you don't know about it.
The mass meter, the air filter and fuel filter will cause power loss.
And i'd run some injector cleaner through it aswell, wynns injector cleaner from halfords will do the trick unless you get the forte specialist injector cleaner.