audi a3 hesitates

[tamiya]

wotcha guys and of course ladies.....my wife has an audi a3 r reg 1800 non turbo...petrol... when she puts it into 3rd gear it seems to hesitate but not all the time..poxy thing... any ideas please its had an oil change 3mths ago hellllllllllllllllllllp .shes looking at taking my car please for the love of all thats good help

[AlBags]

Check throttle body is cleaned out (with carb cleaner)
Check TPS device on throttle
Check plug leads (if not coil-over plugs .. It "could" be a coil-over if it is)
Check plugs