just had hybrid turbo an front mount fitted when i put the engine back in a month ago but now it has this problem. its fine everywhere in the rpm range but it starts doing this when im backing off the throttle to maintain a speed. an at very light part throttle it does it aswel. ive changed the plugs an i noticed there is a knick in one of the leads but i carnt see it being that. i carnt hear any air leaks. any ideas? thanks.[/list]

Take a look at the inside of the distributor cap and rotor arm. I had a fault that started much like this and ended up with a wrecked rotor arm.

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GT4DC Events Co-ordinator
1996 ST205 UK

If it's a 185 then look for an air leak, especially atmos. dump valve.

Misfires due to poor ignition are normally worse at higher boost.

Also worth a look inside the dizzy cap to check the rotor arm is tight.

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If at first you don't suck seed, try drier grain.

Prob compressor surge flutter. Is it a 185? It's more likely if it is... also dodgy bov can cause this....

yeh st185. no dump vavle. running 12psi. will check rotor arm tomorrow.