Truck will be going to the dealer either end of this week or early next. Fuel pressure is in green on the graph above...it is dropping at random times. When it drops Afr goes lean, so the throttle plate closes to protect the engine. Just not sure if the fuel pressure dropping is a cause or a symptom. It could be limiting fuel because of the timing chain, but you have to use IDS to monitor the timing. So going to have the dealer do that...and if that checks out they will have to try and figure out why fuel pressure drops. Hopefully close to having it figured out.