Rough idle cutting out :(

[MARK_GT-APEX]

hi guys,
i know im new here but i hope you guys here can help me. here is my problem

first off, ive checked for fault codes, replaced plugs, it got a fuel filter at the end of the summer.

as im idling in traffic at 800-900rpm it'll be grand not a bother, then a big miss will come in, it will drop to 400rpm or so then regain right away, it might do tis 3 times, it might do it once, it might not do it at all. but its been doing it more than before. sometimes th miss is bad enough to stall the engine, then ive to restart it. it happened to me 4 times this morning on the wat to work. it was idling fine then a massive misfire and cut out. i started it right back up and it was perfect . please help

oh and its a 4age big-port T-VIS MAP SENSOR standard exept for ehaust