fluctuating rpm's

[Kool-aid kid]

2003 ram 2500 5.7. Just changed coils, plugs and wires. new air filter. Starts and idles good but can feel a little roughness in the idle. twice since the tune up it has missed roughly after starting. Giving it some gas did not smooth anything out. But if I shut it off and restarted it everything was then ok. These two times I mentioned probably were a week or 2 apart. I started it today and let it warm up and played with giving it gas while sitting there in park. 1st I attempted to hold the tach at around 1500 to 2000 rpm. It would hold that for a few seconds and then fall 4 or 5 hundred rpm then it would rise back up and fall again, back and forth. I experimented with more rpm and at 2500 rpm it would only loose a couple of hundred rpm. Again up and down. Above 2500 I didn't have any rpm fluctuations. Any Idea's would be appreciated. Going to try some injector cleaner and will try to get a gauge to check fuel rail pressure.

 

[Kool-aid kid]

I didn't mention, no cel except for the fuel evap system which I've been to cheap to fix.

 

[ibike]

I didn't mention, no cel except for the fuel evap system which I've been to cheap to fix.

Elephant in the room?

 

[Daw14]

Is it surging under load ?

 

[Kool-aid kid]

No. Its not surging under load. In fact it seems fine out on the road doing 60 or more. I haven't had it do the rough idle and missing for a week or so. maybe I need to go put my foot in the throttle hard and let it eat and see if it acts up.