My 95 WRX doesn`t pull cleanly above 5k rpm.Seems to be holding back & lumpy.Had recent full service, new plugs etc, coil packs checked & ok. Any ideas??????

 

Was it fine before the service?

 

problem was there before, garage seemed to think the plugs were to blame. Has got worse recently, does`nt do it all the time, lower revs fine ?

 

MAF possibly.
Does the garage have a Select Monitor as this can measure the voltages of the sensors and show if they are within the parameters they should be.
Or see if they have a known working MAF that you can borrow.