Peugeot 307 SW - sluggish engine - mandy68

I am looking at a 307sw 2ltr 110bhp 03 reg. the body is in exceptional state but on test drive it didnt impress (compared with others driven same model) . could it just need a 'clean out' or something similar to return performance, or might it be something mare serious. it has a tow bar which the vendor INSISTS has never been used. any advice welcome thanks.