86 Lincoln with 302 v8 with HO Mustang engine won't take gas & shuts off.

My 86 Lincoln Continental developed a bad oil leak at the Lower Intake, so
I put the vehicle in garage to repair. To be sure, decided to have mechanic
replace all engine gaskets and seals. However, when he put the car back
together, he found it would resist taking gas and shut off. Figuring, one of
the gaskets might be bad, he tore the car down and again replaced for 2nd
time all the engine gaskets and seals to include the thermostat and PCV
valve. He put the car back together a 2nd time and regretably, found there
was no change. If one gingerly applies throttle, sometimes, the car will
crank and then will idle fine,but then if you attempt to apply fast throttle, it
will again resist and shut off. Has anyone ever experienced anything like
this? We are desperate and about out of ideas! We ran a pressure test on
fuel pressure and it shows fine. Also tested plugs and plug wires and fuel
injectors and all test good working order. Also, tested the TPS and it's fine
with right voltage. We welcome any ideas as my mechanic is Stumped!
Thanks. CDH