2005 Sierra Stutters
 

My 2005 Sierra w 4.8 is giving me some grief. After the engine is warm the engine will sometimes miss while driving on the highway. It feels like an engine stutter. RPM drops about 1000 then comes back right away. It might happen 2 or three times in quick succession then go away for the rest of the trip.

At first I was working on the assumption that the problem was electrical. I've found other online posts that mentioned poor contact at the battery or a poor battery ground connection. Checked and cleaned those.

The last time it happened I was looking right at the tach and noticed that it wasn't a momentary total electrical failure as I first suspected, but just a quick series of 1000 rpm stutters. When it stuttered I stepped on the gas, the truck speeded up, and the problem went away. It didn't return for the rest of the trip.

Some have suggested fuel pump issues. I'd like to be a bit more sure about that before I commit to a big job like changing the pump. I ran a code scan before and after the trip an there were none.

I have cleaned the MAF sensor and did a Seafoam treatment through the intake manifold. Clean air filter. Changed gas stations for the last tank to make sure it wasn't the fuel.

Have not checked the fuel pressure yet.

Ideas?
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