I have changed and cleared o2 sensors.
New crankshaft sensor and relearn done.
Replaced PCV valve and vacuum line.
Cleaned the butterflies at the front intake.
Put a new k&m air filter system on.
Changed fuel filter.
still getting a 310 code and random misfires code
the plugs are less than 3 months old as well as plug wires

When driving I have intermittent power below 3k rpm and the automatic shifting is off like there’s a vacuum leak. I think I can hear a vacuum leak when driving, I just can’t locate the vacuum line and don’t hear it at idle.

any suggestions?

 

Is there an aftermarket cold air intake installed? They tend to be noisy and make all sorts of noise. Double check the intake air tube connections, and make sure your mass air flow is tight. PCV lines to the valve covers. If it all checks out, I would go for the intake manifold gasket. Don't forget to check all vacuum connections on the intake manifold. Depending on the year, you might have one on the back of the manifold unless you have the hydro boost brakes.

You can also spray various things around the intake manifold while idling to locate a vacuum leak. Most of us use something like engine starting fluid or flammable brake cleaner, you will hear the idle pick up when you find the leak.... But very short bursts as it is very flammable. Some people use soapy water, I understand the idle will slow down if you find the leak.

 

by your statement i am guessing you have a 2003? (Changed fuel filter.) the truck is going on 22 years old. you might be experiencing clogged cats or cracked exhaust manifolds or both.

 

I just reread it and realized you said you put a k&n air filter system on. Those tend to make a lot of noise, which does sound like a huge vacuum leak. Did you inspect the spark plugs, looking for one that is totally White? (Which would mean running too lean)

 

I cannot find a 310 code for a GM truck, maybe I'm looking for the wrong one,

years back someone had issues with the seals in the air intake system folding under and allowing un=metered air at the MAF and throttle body into the intake track, easy enough to check.

Neal

 

Welcome.

Year and Miles??

When was the last time you cleaned the Throttle Body with Throttle Body Cleaner and cleaned the MAF with MAF cleaner?

 

P0310:
Misfire on #10 Cylinder?
Digital Cross-Connect (DXC) Technology is unstable!

 

Yep, seen that one but figured he had not installed a ford engine in his truck

Neal

 

Could be as simple as sparkplug wires loose. Always good to give them a good push in and pull up. Looks likr they are on but not connected.

 

That code and no low torque =…….

It is plugged cats. And it is expensive fix if u stay with OEM, as it is an entire assembly u r buying.

Confirm with testing pre and post cat O2 sensor air pressure differentials. Usually only pax side goes first.