i need some help her please anyone , got a 94 vr6 missfireing all over the show hot or cold , starts from pull off and by 5000 revs is backfireing , its got fsh and 103k , ive replaced plugs used fuel treatment the leads are new ish and ive tryed water testing them , changed the coilpack for a new one , its had a fue good runs and its getting worse now ive had it plugged into a vw computer system and theres no fault some one has said injecters or mab a valve any idears would be great