Engine running rough after storage

I use Lucas fuel system cleaner. It works awesome. Run a few tanks and it smooth's out and the MPG goes up usually a couple.

You had some fuel dry up in a critical spot and it ran rough until it cleared.
I would either run a few tanks of Chevron with Techroline through it or dump a can of Seafoam in it. SF is the only "snake oil" type product I've ever seen that actually work.
It's cheap insurance!

You had a couple or more injectors leak down over the storage period. If you want to clean your injectors, etc add 1 quart of cheap, available at certain sources for $2.90/qt, ATF/20 gallons of gas and hit the road. Run that tank out and fill it up again and it will run much smoother. ATF is a lot cheaper than "injector cleaners" and does the same or a better job.
Randy

SEAFOAM, enough said. I use it in everything I own. Great for the onan also. I have cleaned onan carbs that would not start or run with seafoam. One is on a friends gen for a year now and running fine. Like previously stated. Cheap ins.

I use Seafoam inplace of stabil. Prior to storing the motor home, I add a whole can to the gas tank. I then drive the motor home and run the genny, each about a half hour, park it and I'm done. This has worked good for us for four years now.

Brian

Right after getting our class C I used Seafoam and it worked great, maybe too great. It really freed up stuff in gas tank, and of course that got caught in the fuel filter, once filter plugged then 2 injectors got plugged up. Then after cleaning out injectors and another new fuel filter, it plugged up the filter again (about 3,000 miles) I changed filter again and then again in another 3,000 miles. Now after 10,000 miles it runs great. I ran Seafoam thru it when mileage was around 100,000 miles. Old owner (Cruise America) apparently didn't waste much money on fuel system cleaner. And apparently the gas is not as clean as the advertisements we see. It runs great now and I run a injector cleaner about every 6 mo. No particular brand but I always make sure I get mixture right.

First I would see if one of your coil over plug got some water in it. Maybe it will dry out after some exercise. If it still does it and if no codes being thrown I would change fuel filter to see if that's the problem.

The injector place where I took my plugged up injectors to tells me that he loves Seafoam. As it brings him customers. By the way I like Seafoam now (even after my troubles) because it really did clean stuff out.

Sea foam fan here.

Thanks everyone for their input. The suggestion that one or more of the injectors had dried has me thinking. I park the rv inside a garage so I don't think water in any of the ignition would be an issue. I have several containers of Techron and will try that simply because I already have it on hand. If that doesn't take care of things I'll go the Sea Foam route. Again, the problem only occurs for a short while like 5 minutes after initial startup and then after that, things smooth out. Once on the road, the problem does not reoccur.

If above posts don't help my next step would be to clean the Mass air flow then maybe IAC. But those are down the road if problem doesn't get solved.

You also had a lot of rain. Engines don't close valves when they sit
Guess I'm the only one that tried Seafoam and it did nothing. Zero. Engine still ran rough
But under circumstances different than yours.