Nissan Repair: stutters @ 2500 rpm, head gasket, backpressure

Question
Hi, just had my head gasket and clutch changed on a '92 Nissan 1600 NX.  
During the test drive, the engine stutters hard at 2500 rpm in every gear.  The
mechanic has no idea what the problem is.
Please help

Answer
Rodney,

Could be the converter is plugged and that is what took the headgasket out.  Have the backpressure checked.  I have seen this more than once.  Other causes are a need for plugs, wires, cap and rotor as well as low fuel pressure.  Those are the top three so have them checked.  Email me back and let me know.