96 Silverado sputtering when maintaining speed

[lukeGG559]

New user and first time posting, but I recently got a 96 Silverado 225k on dash, runs solid BUT i noticed whenever im maintaining speed like 45mph+ (cruise control or just steady pedal) the truck will sputter it feels like a light jerking. Possible popping from exhaust, its a little hard to tell at high speeds with all the noise. It has a po1345 code and a O2 sensor code... would these codes cause symptoms like that? truck runs awesome in town, no hesitation or anything. Also should note at higher speeds i can gas it and it jumps up n goes no hesitation. only when holding speed.

 

[Cadillacmak]

I had that with my 97 suburban, turned out to be the distributor. Pull the cap and if its really sloppy that could be your issue.

 

[lukeGG559]

I had that with my 97 suburban, turned out to be the distributor. Pull the cap and if its really sloppy that could be your issue.

i think the prior owner did mess with it, i found a box for cap n rotor in the storage compartment. maybe he didnt align it correctly

 

[Schurkey]

The plastic distributor is known for several problems. Inspect it carefully, out of the engine if possible. Correct the distributor alignment when you reinstall it. This will require a scan tool.

Replace the O2 sensors.

Also:

The Usual Three:

1. Verify fuel pressure at prime, at idle, and under load. Most fuel pressure gauge assemblies have a push-button pressure release connected to crappy vinyl tubing. Route the tubing so it empties into a drain pan, then push the button while the engine is running. This simulates higher fuel demand if you can't check fuel pressure on the highway. Fuel pressure should remain steady even with fuel flowing down the pressure-relief tubing. How old is the fuel filter? Have you ever dumped a bottle of Chevron Techron Complete Fuel System Cleaner into the gas tank? (Recommended at every oil change.)
   
2. How old are the usual “tune-up” parts and procedures? Inspect/replace distributor cap, rotor, plug wires, spark plugs. Make sure the ignition coil will reliably fire a spark-tester calibrated for HEI when the coil is fully warm, and misted with water from a squirt-bottle. Cranking compression test of all cylinders while the spark plugs are removed. Verify EGR, PCV, EVAP, and Heated Air Intake (if used) systems for proper operation. Verify proper initial timing (TBI) and electronic spark advance (TBI and Vortec). Replace old O2 sensors unless you can PROVE that they're working properly—old O2 sensors get lazy, they don't provide accurate data, but they do provide “data” that fools people into thinking they're “working”.
   
3. Connect a scan tool (NOT a crappy “code reader”) and look for “codes”. More important, look at the data stream to verify EVERY sensor and computer output. Verify fuel trims during the time that the vehicle is not running properly. Look for misfire counts for each cylinder (OBD2 only.) “Codes” have official diagnostic procedures that will be found in the service manual set for your vehicle. The service manual set can be downloaded from the links in the Sticky thread section of the Engine forum on this web site.