I started having a problem with accelerating about a month ago and I finally got the money to replace the MAF. While this did help it is still far from running like it should. It is throwing a EGR valve code and it has a random misfire (could be a specific cylinder I checked it right when the light came on they normally figure out what cylinder the more you drive). My initial problem was gradual for the record as well. Also there was a vacuume like off from the fuel pressure regulator to the other side of te engine I forget what it goes to. But if that line is on it will constantly cause the car to stall out when I let off the gas so I have that disconnected so I can drive it actually without getting stranded. I'm thinking the misfire is probably a bad plug or wire fouling out because I drove it for a while probably too long before I replace the MAF. What could be causing the car to stall out when my vacuume lines are hooked up? Also could the bad EGR valve cause it to not accelerate correctly at low RPM?

 

have you tried hooking the vacuum hose up and then starting it? have you tested fuel pressure? when you hook up that hose it should bring the fuel pressure down, if fpr is failing it may be dropping a bunch and killing the engine. testing will tell.

 

Random misfire is usually the result of a lean fuel mixture. The fuel pressure regulator uses the vacuum line to control fuel pressure. High vacuum (line o) leans the mixture & low vacuum (line off) richens the mixture. By disconnecting the vacuum line (low vacuum) you are forcing the regulator to richen the mixture. You said the engine will stall with the vacuum line on. To me, this indicates that either the fuel pump is weak or the regulator not working properly, either one can cause low fuel pressure. As Craby said, check the fuel pressure.

 

Are either of those issues, things that can go gradually? Because the whole problem was a gradual thing. I fixed the MAF and its running better just has the misfire, may be cylinder 5 haven't been able to read the codes lately.

 

yes the fuel pump can weaken over time as its an electrical pump. the fuel pressure regulator might but since its powered by vacuum I don't believe it would.

 

Ok I have found out that my EGR valve is bad. These can effect the misfiring can't it? Also could that be a reason why i have to disconnect the line from my fuel pressure regulator in order to keep the car running? Also I had someone look at it and said that it needs new head gaskets because of the bad CAT converter? I have never heard of that I didn't know if that could cause some of the symptoms that I am having.

 

As the other guys said check fuel pressure. Scan the codes and write them all down and tell us what you got so we know whats going on better and we can point you in the right direction.

 

never heard of a bad cat causing a head gasket to fail. intake manifold gasket could cause your issue.