1990 350 chevy in a itasca motorhome in park rough idle in drive it backfire in carb and dies often

Not likely, but a worn camshaft and timing chain will.

What about the Idle Control Valve I know these are a common fault on Ford's, if so you should be able to get away with taking it off and cleaning with something like carb cleaner. Maybe fuel filter needs changing is that the one you meant you changed?

this sounds more like you need the carb rebuilt to clean out all the dirt in the small passages and replace the needle and seat as well as the float. the idle air mixture screw are at the front of the carb at the base one for each barrel the carb has. this year should have tamper proof plugs covering the mixture screws which the carb will have to come off to remove them.

How many rpm's is it running at when you first start it up and it is running on the choke? Does it gradually start to idle back and then start to die r does it do it all of a sudden and dies?

When running with the choke on, it is on the high idle circuit of the carb, as it warms up the idle should slow down and then idle in the 800 rpm range in Park, 650 in Drive. This will be the low idle circuit range. This transition inside the carb will cover an idle air bleed hole in the venturi of the carb and lean out the mixture. If you notice that the carb smells gassy and black rich unburnt gases are coming from the tailpipe, the problem is located within the carb and requires a carb tech to do a rebuild of the carb. You could try a good carb cleaner like Lucas by putting it into the gas tank, in case you just got a bad tank of gas, but that is just a bandaid for a more deeply rooted problem. Get the carb rebuilt?

remove carb then put on a sheet of newspaper and give it a good clean out ,could you have filled up with diesel ?? have a sniff and see

Please replace your COIL with new one.
Regards, Jay

poss u have a miss or ur idle is way to down did u do a tune up?

almost sounds more in the carburator. if this motorhome sat for a long period of time, when you opened it up, it increased the fuel flow in the bowl of the carb, therefor may have stirred up dirt and varnish. id check there first. if it has a holley on it, if it "coughed" or backfired through the carb when you "opened" it up, it more then likely blew the power valve out

your coil could have went out on you.

a cheap and easy thing to try is to clean the carbs. get some carb cleaner and run through your next tank of gas. Also a batch of bad gas can cause the problem too.