96 Dodge Ram running rough

96 Dodge 1/2 ton pickup with a 318 and 120,000 miles. It is running rough and stalls off and on.. Does this warm or cold. Previously had a code reading 301 Cylinder misfire detected, but ran fine at that point. Since the problem has started it now reads 16 codes. P203 P202 P205 P207 P208 (Injector Circuit Open Cylinder 3, 2, 5, 7, 8.) P300 Random Multiple Cylinder Misfire Detected. 301 302 303 304 305 306 307 308 (Cylinder 1, 2, 3, 4, 5, 6, 7, 8 misfire detected) P0441 Emission Control System Purge Flow Fault. P0711 Trans Fluid temp Sensor A CKT Range Perf. I think the trans sensor is unrelated but the other 15 codes may have something in common. Does anyone know what would set them all off at once and cause the truck to run rough and stall?

Check the plenum gasket first, http://dodgeram.info/tsb/2000/09-05-00.htm. If it's blown, than more than likely the cat is bad too.

I shot starting fluid all around the intake, figureing that if it was sucking air in somewhere it wasn,t supposed to because of a leaky gasket that I would be able to hear the motor speed up and then I would know that was the problem. Nothing happened. Then on a gut feeling I unplugged the battery and let the truck set for 30 mins or so...when I plugged it back in and started the truck the check engine light was off.... I drove around 8 miles or so at aprox 30 mph and it seemed to act fine. I guess the real test will be in the morning when I take it to work on the highway. That is where it usualy stalls and misses, ect.

The gasket I'm talking about can not be tested in that manner.

Is the gasket you are talking about the one that goes in between the two halves of the intake? And if so is there any way of testing that without taking the intake off and replacing the gaskets to be sure?
oh and fyi reseting the computer didnt work....lol sounded to easy to be true.

I gave you a link in my first post on how to check the pan gasket.

you need to remove the pcv valve, plug all valve cover vents and all that and check your oil dipstick tube for vacuum, it should be pressure

did you check fuel pressure?
are your spark plugs clean?
could be dirty fuel filter

This is odd, but I had a 96 dodge ram van that the fuel pump got stuck int the middle of the tank. it would not go to the bottom where the bracket holds it. it kind of got pushed up the blue plastic holder which was amazing. About 1/4 tank it starting sending misfire signals because it was out of fuel.

I had to drop the tank. where the fuel filter is. The fuel filter was spotless clean. I looked at the fuel pump housing and I found the fuel pump had been pushed upward out of position. So it was not sucking fuel from the bottom. WEIRD SITUATION! took me a week to figure it out!

Turns out it was a poor distributor cap that was 90% of the problem.
Thanks for all the help.