Hello. I have a rough idle and when I drive it switches gears and around 45-50 mph it’s starts shaking lik it’s bogging out I get a code p0304 and p0300 I think I have a exhaust manifold leak would that cause it to misfire? I check the vacuum it’s at 20 hg. I’m stumped any help is greatly appreciated thank you

 

What engine?

 

2004 5.7

 

What year? Some of the hemis have issues with breaking exhaust manifold bolts..... but, a leak shouldn't give you a misfire. The shaking is likely a result of the misfire...... you have a hard code on cylinder 4, and it's also whining about random cylinder misfire. When is the last time you changed spark plugs? How many miles on the truck?

 

It's a 2005 truck the motor is 2004 when I swapped I took the plugs and changed all 16 plugs so there brand new when I changed the coils and wires some blistered the spark plug so idk how long he drove like that but I changed then all with fresh plugs and wires.

 

There's 200000 miles I'm at work but it's around that

 

Any idea how many miles on the motor?

 

Pretty sure it's around 221000

 

 

Yes, and yes. Bad O2 sensors can lead to a bad cat as well. Disconnecting them simply takes them out of the loop, so, the PCM ignores them and runs the engine off tables...... If it runs better with 'em unplugged, just replace them.