2001 Mercury Cougar Cabin Air Filter "tbi fuel systems" Questions

...fuel filter & pressure regulator in tbi. Replaced coolant temp. sensor. Fabricated EGR gasket with no holes in it to eliminate the EGR valve. Replaced EGR gasket . Replaced TBI to intake manifold ...

vacuum diagrams in these books that should points you in the right direction. Given that it idles in a rather manic/depressive manner, I'd look to the carb/TBI/Fuel injector system for a vacuum nipple