I am starting to think that the injector argument is holding water. The vehicle when left in drive at idle will consistently get loaded up and start to miss and eventually die. If you throw the car in neutral and keep the rpm over 1k all is good with only slight hesitation when back in gear and driving off. When the car is driving down the road there are no symptoms.

Tomorrow I am going to allow the car to Idle in gear till it dies (consistently replicable now) and pull the plugs and see what they look like.

Any other ideas for me to check (EHA, cold start leaking etc.)? looks like I should then pull the injectors out and test them.

Am I making sense on this? Thanks to all for replies.