Sorry to hear that mate, and I might be down the same path as you.
I have the same problem, it's intermittent.
Doesn't seem to do it in 1st or 2nd, hammering off the mark but does it in third gear with my foot down.
It's a loud droning burble under the car, not at the engine or at the ass, no power.
My mechanic has checked and all diagnostics are normal.
I had him check the AFM as this could be the problem but it reads fine.
Have you had your cat checked for blockage ?
However I have leaking stem seals and oily /fouled plugs so I'm putting my money on bad spark.
Got told today it's engine out to fix stem seals...