poss coil pack fault?

i had a vibration that came at 2750 and goes at 3100 rpm, some times worse than others! i recently removed my irridium plugs to clean and regap, vibration now at 1900 to 2000 rpm, have binned the irridiums as they where rubbish and fitted the equivelnt NGK's regaped to .7mm (for lpg) and although its runs so much better the vibration (1900-2000) is still present.
i have since fitted brand new magnecor leads and the vibration although better is still present, most people dont notivce it unless its pointed out, but its there and i notice it..............
could this be a coil pack fault? the fact it moved from around 3000rpm to 2000 rpm by cleaning/gapping the old plugs tells me it cant be mechanical, must be some sort of misfire, somebody here sugested this ages ago and i disagreed, who ever it was i must apologise!
is it know for the coil pack to give this type of problem?

P.S. 1996 4.6 hse lpg with recent engine rebuild

anyone?

Scope your HT leads.

eightinavee said:

Scope your HT leads.

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how you mean "scope ht leads" could you explain this please?

I mean check the waveforms of the HT side of the ignition with an oscilliscope - this is the best way to see if all is in order.

eightinavee said:

I mean check the waveforms of the HT side of the ignition with an oscilliscope - this is the best way to see if all is in order.

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il give it a go, can i assume the leads just plug in to it, or pass through it like a timing light? and il have to get one as well, sounds expensive so maybe hire one?

Mine was £800 so I'd look for a garage that has one - look in yeller pages for a Bosch Diagnostic centre they will have blokes/kit that can give you the answers you need.

thanks guys.