Ok I have a 2001 dodge ram 1500 sport with a 5.2l. Every morning for the past couple days, the motor has been shaking as if it was misfiring. It doesn't shake violently, but enough for me to notice. Also there is no codes and I put factory plugs in about 1000 miles ago. It only does this on a cold start runs great when warmed up. Anyone have any ideas? Also the average mpg is at 9.6

 

there is a technical service bulletin about wire routing, try that first. also go out at night and see if there is a light show under your hood, may lead you to a bad wire. Did you gap your new plugs?

 

Yes there are gapped to factory settings .040 and ill re-check the wires with that TSB

 

I'm with gertie, check your wires and/or replace them if you didn't do that when you changed the plugs.

Also check your distributor cap, it may be cracked.

 

Dizzy cap with brass terminals, and a piece of plywood to lay across while working on it.

 

^Dude, I just said that!

 

Wires seem to be routed correctly. Today while letting it idle I heard a pretty loud whistle as It was a vacuum leak. Right after that I revved it up and after that it was idling normal for about 20 seconds and then it would start idling rough again

 

Clean throttle body, paying careful attention to the IAC, and its well. TB gasket is like two bucks.

While TB is off, have a look at the plenum..... I bet yours is blown.

 

Last time i checked the plenum didn't seem to be blown, it doesn't consume any oil, there is no knock or pin. Any possible chance it could just be the upstream o2 sensor?

 

Entirely possible. But, O2 doesn't really start doing anything till the engine has been running about two minutes. If your problem starts reliably at that point, I would replace the O2 sensor. If you have over 100k miles on your truck, I would replace it on general principles.