intermittent misfire & power loss

[wingzero25]

Lately my car has been losing power under load, most of the time it sounds like a tractor the past 6 days & very high shaking of engine, sounds fine on idle at around 900-1000 rpm, if it exceeds that then shaking & tractor sounds.

here's what I've done so far:

Cleaned injectors
Changed x4 spark plugs
Diagnosed with no fault codes to report
ignition coils or coil packs are apparently fine

No change what so ever except occasionally it runs smooth, misfire, smooth, misfire, smooth, misfire! not to mention the jerking!

What I'm checking next:

ignition leads
MAF (Would it be safe to disconnect this temporarily?)
fuel pump

is there anything else I should have checked?
is this a common fault?
it's a V 1999 1.6 automatic saloon.

 

[foursprungdugtechnique]

Try removing ONE plug lead at a time with the engine running, good idea to wear insulating gloves! If the engine note changes the lead/plug is usually fine, if no change that would indicate faulty plug/lead.
It's ok to disconnect the MAF, you'll get the stability control light (yellow) on the dash it's something to do with abs/power to engine./stability setup. Light will go back off when reconnected

 

[jbh]

as above disconnect one coil pack at a time.
also I would do a compression test on it.