it sputters realy bad at low rpm.it ran fine 4 days ago, then the fuel pressure regulator went.i replaced it and it still runs like crap.it even sputters at higher rpm.its ok at mid rpm but not like it used to run.ive replaced just about every sensor on it.could it be either a head gasket or an intake gasket?or maybe something else?? please help me .Thanks

it sputters realy bad at low rpm.it ran fine 4 days ago, then the fuel pressure regulator went.i replaced it and it still runs like crap.it even sputters at higher rpm.its ok at mid rpm but not like it used to run.ive replaced just about every sensor on it.could it be either a head gasket or an intake gasket?or maybe something else?? please help me .Thanks
Need more info.
What engine and what is the fuel pressure readings?
How is the ign system?
Good Hot blue spark?
Plugs and wires and dist cap?
Any codes or check engine light?
Any engine cylinder misfires?

does it idle rough? may be egr sticking open.runs fine while driving but rough idle.