my car has been surging for ages now but it never really presented that much of a problem untill now.

it will do it from the moment the car starts untill it reaches that first yellow line on the temp gauge (just before "normal") it misfires right after each gearchange (only at less than 2/3rds throttle) and at very low RPM (under 100) with a sudden change in throttle position whilst accelerating if i push it a bit harder it gets over it and revs climb as usual, untill it shifts al whilst its surging all over the place (sometimes its a good 150rpm change in revs) once its warmed up the problem dissapears completely (although a very slight surge is still there sometimes) under full throttle no loss of power is evident and it runs great.
one of the guys at work said he saw some "smoke" from my car when i took off, but its not due to oil/coolant cos headgasket (with valve seals) has just been done

lately ive done plugs and leads, ran a tank of injector cleaner through it and changed fuel filter.
No exhaust leaks are present BUT there is a pretty loud rushing sound from the cat/extractor area (but no leak)

im thinking it could be a part of my old cat (other bits came out the back) stuck in the front muffler OR something wrong with the current cat (better not be its only 6months old)

could be dizzy problem (a sudden retard in the timing would seem to explain the problem but i dont know enough to be sure)

i know what MAY be causing all of this (just about every sensor in the bloody car) but im after a more definite response (like if someones car was acting exactly the same or they know exactly what it is.

any ideas?

When my cat collapsed the car behaved pretty weirdly.
One surefire way of telling is to tap your middle muffler, and listen for chunks of cat bumping around in there
Also, my dizzy retarded base timing over a period of time, due to a certain mechanic not securing it properly...
Some ideas there to check.

coil.

Sounds like Coil to me as well.....

it could be a coil, or better yet put it a a diganostic check thingy to check the how car computer system.

I suggest coil or dizzy. With the dizzy you might want to pull it out and check it's shaft for any wear and tear (slipping on oil pump???) while under load.

get a diagnostics test done,,,,i have had ver similiar issues and found my cam sync sensor was rooted....after it was replaced the cars runnin great again (EF XR6)

i had this problem on my EB turned out to b a little hole in the inlet manifold.the surging only happend at low revs.

thanks guys - need to check:

Vacume leak (whats the easiest way)

then start replacing stuff - coil and dizzy.

ECU fault codes were pulled not that long ago and nothing showed up then so that ones out.