rough after start-up

[DUNE RCR]

So I just bought my wife her own 06 xlt with a v6 and everytime she starts it it seems like its going to idle out then revs up to about 1500 and after about 5 minutes it kinda smoothens out. Other problem, not sure if related, while driving down the highway at about 55, occasionally it will feel like it is miss firing. My question is what are the probable causes? I'm not used to everything being electronic. Thank you for any info.

 

[DUNE RCR]

Anybody have any ideas?

 

[92exploder4dr]

Take this with a grain of salt but intake manifold leak? Could be upper and lower intake manifold gaskets? Everything expands as it gets warmer hence it idles better after 5 minutes.

 

[Explorer_PL]

My v8 was missing because 1 sparkplug was bad. It's not a badidea to replace them anyway.

 

[DUNE RCR]

Take this with a grain of salt but intake manifold leak? Could be upper and lower intake manifold gaskets? Everything expands as it gets warmer hence it idles better after 5 minutes.

Thats the problem it acts up after it is warmed up, runs fine cold.

 

[DUNE RCR]

My v8 was missing because 1 sparkplug was bad. It's not a badidea to replace them anyway.

I was thinking of doing a full tune-up, havent had the money to do so just yet. I had noticed with my v8 that if one cylinder was missing you wouldn't notice it to much until under load but let 2 plugs missfire and all hell will break loose. I miss the simplicity of older cars with carbs and distributors.