Leak test should be on the very top of your list. It should have been the very first thing your shop did before swapping out parts. If this has not been done on the car, move it up to #1.

 

The vacuum hose comming off the fuel pressure regulator made my car do the same exact thing.

-Ed

 

This does sound like an intake leak, but it could also be on the fuel side. One known problem in these cars is the fuel pump, in particular there is a hose inside the tank that tends to split.

This is pretty easy to check: disconnect the battery, then the electrical connector and then fuel hoses, then unscrew the plastic retainer ring and pop off the top and look inside the fuel tank. The hose that tends to split is black (the others are translucent white). Might be a good idea to take a cell phone picture first, and mark the location of the retainer ring against the cap.

 

02 sensors are mounted in the exhaust & sense oxygen content,thereby letting the ecu make changes to the amount of fuel going in to the engine.If they give a false reading you get the wrong amount of fuel to run properly.There are 4 02 sensors,the 2 before the catalysts perform that funtion and the other 2 just ck the catalysts.A poor seal between the airbox to throttle body or as mentioned intake vac. leak will also make the 02 sensors read incorrectly.The 02's are not too easy to ck w/o proper diagnostic equipment or familiarity w/ correct function