Have you tried a compression test?

rpm loss
 

You mentioned earlier that it almost seemed as though it was a lack of fuel!
Could there be a fuel pump problem?
Was the motor changing rpm slower then faster?
I had a problem on time with contamination in the fuel tank a plastic cap floating around in the tank, inconsistant fuel delivery causing rpm drops only on occasion, a tough on to trouble shoot, we pulled the fuel tank and found the plastic plug.
Post your findings.
Thanks

It's Back!
 

Yesterday morning before work I decided to start breaking down the exhaust etc so that I could pull the valve covers. i decided to pull all the plug wires and get them out of the way. When I did this I noticed that the positions of 1 & 3 were reversed in my wire seperator hmmmmm....... I'd checked those wires at least five times but they evidently were twisted behind the exhaust and a pull on one moved both.

To make a long story short, swapped the wires and it's all good.

Thanks for all the help.

Glad to hear it!
 

:D

Plug wires
 

Looks like your going boating!
Thanks for posting your findings.
They should make a design change in all ingition wires with different colors and or a more perminant type of method to stick on or crimp on a solid number with a stainless steel number.
I typically like to use a paint stick, and write the cylinder number on the plug end of the wire.
Have a great day
Brian