My Car Is Surging On De-exceleration -whats Wrong-?

[O.I.C Napster]

Hi all,

My other car a mazda 626 2.2L turbo, is surging on de-exceleration second gear third gear etc. It wont do it at high rev's but about 3000rpm it will be like its putting on the brakes and taking them off quickly. Im unsure why its doing it.

Its had a new turbo new gearbox new diff new 4 point injection system, new tire rod ends new cv joints new steering rack FMIC POD Stinger ECU and full tune. (still runs like a piece) but its an old car. Bacially a new car apart from touching the engine.

But basically i cant work out why its started to do it, BTW it also has a small exhaust leak **maybe that has something to do with it**

Any ideas people please note em down on what i could try and do.

Thanks for ur help

Matt