How is the fuel pressure ?

Maybe try and disconnect the battery for a 1/2 hour or so,,,
check O2 sensors,,,
What about a mouse nest,,,or worse an exhaust packed with corn kernals,,nuts, acorns,,little basturds,,,Dont laugh,,,they got in through the Headers on a Buddys 69' Camaro race car,,,,packed a couple cylinders full,,bent a couple valves,,,,,he was pissed,,,you said it was sitting 7 months,,,,,!!!