importedrx7

ok here is the thing my friend has a 89 GTU. A lil while ago like two weeks he put a pacesetter header on the car he could never get the car started he finally gets the car starts but has to hold the gas down to keep it runnin. well we take the header off today and the cat end of the header drops to the ground oil and gas start spewing out of it i mean it was full of it...? ok what is the problem if there is that in the header????02 sensor was pluged in to????? im lost i mean **** just came everywhere. need help asap?