Aw c'mon!! You're killing us with suspense! Ok, here's a long shot. When it's warmed up, just as an experiment, take the vac tube off your EGR where it connects at the transducer and hook it direct to a port on the throttle body chamber and see if the power returns. DO NOT drive around like this! You will be pulling loads of hot exhaust gas into the throttle chamber that will cook the day lights out of it and anything attached to it if you run it for more than a minute or two. Just pull out of the garage and back in. If the power has returned the EGR circuit IS the problem. The trouble with the finger push/engine dies method of EGR check is the EGR port can be clear but, that doesn't confirm you're getting vacuum to the EGR. The EGR works in such a narrow range of throttle positions it's tough to check the vacuum too. Presuming you checked out that little thermal valve that feeds vacuum to the transducer (top-shaped brown thing) pull the bottom tube off the transducer with the engine running. You should feel hot exhaust gas coming out of it. If you do not feel hot gas you need to take off that steel tube it attaches to (firewall side of throttle chamber) and clear it and the opening it threads into. Mine was so gunked up with carbon I had to use carb cleaner and a drill bit to clear it. Second thing is check the top of the transducer. If it looks bubbled or scorched that means the membrane burned through and it's not going to work. Replacement is the option. The back pressure transducer only uses the pressure from the exhaust system to actuate and send vacuum to the EGR. If hot gas is getting by, the transducer is defective and the EGR won't work.