2005 Ram 1500 5.7 Hemi, did something the other day it's never done before.
It started, idled and drove out of the yard fine. Pull out on the road and lightly start to accelerate, and it starts acting like I'm on and off the throttle really fast, fluctuating up and down, but I'm keeping a steady push on the throttle. I back off and keep the throttle just enough to do about 30 mph and its fine. As soon as I push abit further it does it again. Push further down and it smooths out for the most part. I drop my kids off at the birthday party down the road (maybe a mile away) and drive out to the highway (about 1.5 miles back). The engines fairly warmed up now so I floor it and it goes through the gears no problem up to about 75 mph and I stop there. Drive around abit and it's fine, even under light acceleration. Anyone ever had this?

Sounds like a possible TPS (throttle position) but lets hope not as they are an expensive part. I had one go on my 04 diesel and it was more than $400. I had about 200,000 miles on it then. Mine threw a code but did some weird crap like you describe leading up to the part failure and check light.

I had a GM truck doing the same, replaced the TPS ( didnt fix it)..

Turned out there was a hole in the throttle body gasket ( where it mounted to the intake)..

Might want to check it....

Check out ur Idle Air Control Valve..
Located on the intake manifold, basically is a small stepper motor works like an EGR...
Usually these get carboned up and the idle starts to act up.

Just my $0.02...

Yes, my 05 neon did the same thing. First, have the vehicle codes checked if any. This sounds like a crank sensor is about to $hit the bed.

Actually the IAC (Idle Air Control) valve does not work like an EGR valve but maybe you mean it has a pintle to block off the air passage kinda like an EGR valve blocks the exg gas passage until it opens. But they are two completely different systems. The IAC is normally a stepper motor but on this vehicle it should be an electronic throttle body that dont have an IAC motor as it has a motor to control the throttle blade position to control all throttle positions. But on vehicle with the IAC I have found that most of the time if you have an idle flucuating because the IAC valve is moving around its not because the IAC valve is bad because its actually working since it moves and changes the idle speed. The problem usually is something is telling the IAC to move and then the PCM is working it. Most of the time when I would get an erratic idle it was a bad TPS as the TPS volts would not stay steady at idle and when ever the TPS volts moves off idle the PCM will open the IAC some to hold the rpm up a little when you let off the gas and then bring it back to normal idle to help keep it from stalling. Basically the electronic throttle body can do the same but it controls idle by the throttle blade position. I dont see that problem as much under light throttle but it can happen. But as said your best bet is have the codes checked and also have it scanned to see just what is going on when it happens. Otherwise you will just be guessing. Even an EGR valve opening way to soon can cause that problem along with other things. Ron