Engine Help!!

[Ros981500]

I have a 98 K1500 with a 305 with 240,000 miles. My issue started about six months ago. The truck idles fine, but when u drive it when you get past 2000rpms the truck starts to act like its chuggin. If you hit the gas it goes away. I have put new injectors, fuel pump, filters, plugs, wires, distributer, coil everthing to do with a tune up. also egr vavle,mass air,TPS,AND ICM. Also had the cam retard checked.No codes reading at this time and none stored.But have noticed small leak in intake. could this be my problem?our is this something i have over looked.Please let me know if you have any thoughts

[MT-2500]

Originally Posted by Ros981500

I have a 98 K1500 with a 305 with 240,000 miles. My issue started about six months ago. The truck idles fine, but when u drive it when you get past 2000rpms the truck starts to act like its chuggin. If you hit the gas it goes away. I have put new injectors, fuel pump, filters, plugs, wires, distributer, coil everthing to do with a tune up. also egr vavle,mass air,TPS,AND ICM. Also had the cam retard checked.No codes reading at this time and none stored.But have noticed small leak in intake. could this be my problem?our is this something i have over looked.Please let me know if you have any thoughts

I would check for good fuel pump and fuel pressure.

The only true test on a fuel pump is to check the direct fuel pressure from fuel pump.
A quick test is to block off the return line and see if fuel pressure comes up to 75-85 lbs.
But do not run the pump at full pressure very long.
Also when testing fuel pump and pressure you need to tape a gauge to outside windshield or outside mirror and drive it on the road for 20 -30 minutes
until the pump gets has run a while to check for a pump fading out after hot.

Hard to start cold or hot and fuel pressure testing guide lines.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
If pump has full pressure with return line blocked and low pressure without it blocked most usually the fuel pressure regulator is leaking or not holding pressure.
Later V6 and V8 gm engines should have 60-66 fuel pressure.
Cold start should be 64-65 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Do not leave home without it.
Engine running should be 60-66 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak in system.
Post back fuel pressure readings.