rough idle in reverse gear??

earlier today my truck started have a rough idle when i drop it in reverse. it seems to happen everytime i park in a stall and reverse out. it will go away once i drive off. i recently put new plugs, and pcv. any ideas?? could maybe one coil is starting to die??

 

Nah I wouldn't mess with those things they really have nothing to do with a "idle" just in reverse. If you had pcv problems you wouldn't really know it unless you had either a code or oil leaking into your manifold.

Plug issues would be more of the lines of poor performance or your missing an a cylinder in which you should feel quick considerably. Very unlikely anyways.

Your going to need to post more information but right off the bat I can speculate and tell you a few things.

1. If you apply break and put into reverse and get a "clunking" noise, followed by vibrations come from engine then it could be transmission mounts. A easy way to check this is to grab your buddy and have him observe your motor or have him in the cab and watch the motor has you apply break and move it into reverse it should move, if it does make a considerable movement then you can bet you have a bad mount. Make sure that blocks are applied to the rear wheels or all wheels and that parking break and main break is applied.

2. Probably not the issue but IAC components and or dirty MAF could cause idle issues but to me its doesn't seem like idle issue it seems like a vibration issue.

How many miles?
Gas mileage decrease?
performance issues?
Clunking? Whining? Ticking?

 

Check your engine mounts.

 

Had some spare time to work on my truck and I took the air filter assembly to access the throttle body. It was really dirty. Sprayed the crap out of it and let it sit, and did it again 30 minutes later. Also, sprayed the MAF with MAF cleaner while I was at it. Had a hard time starting and threw a cel. The rough idle in reverse seemed to go away at this moment. I may try seafoam next time around. My truck has 180k, 4.0 v6. I may replace the engine mounts just for preventive maintenance. Which one usually goes bad??

 

Ran sea foam multiple times and I wouldn't recommend it. Honestly the only time I would use it would be running it in your engine oil after a oil change and through the tank. Don't run it through the throttle body these newer engines don't like it and your MAF won't like it.

Just my two cents sea foam can be good only if used certain ways. My 03 stang didn't like it to much.