I have a 2002 Dodge Ram 1500 4.7L. Just recently it started to have intermittent missing on 3 cylinders. Changed the plugs and swapped coils, still happens. Have a hard time beleiving it would be electrical if "all of a sudden" three cylinders started missing at the same time. Any thoughts?

I meant, I have a hard time believing three coils would sudden all fail together.

I am not a major Dodge tech but may pull the coil pack off to look it over for cracks. Tell/tell sign it has gone bad.

I swapped out coils, still misfires. Will try seafoam in case injectors are fouled.

Fuel pressure may be low, check for low fuel pressure. If fuel filter is old may change out for a new one, Rockauto says it a type fuel regulator filter. May need to check regulator. Injectors may be dirty. Otherwise ECU/PCM may be bad, and for those models you can not just change it out for any computer, you have to mail yours off to company and they will send you another programmed per your vin number or fix yours. We did this on a 2002 Dodge about a year or so ago for a different issue and we use All computer resources for ECU's as they are fast, very reliable. I will post the web URL home page below by itself, under the shop by make click on dodge and BTW that page also has arrows you can click on to go to all the other car makers brands in-case anyone needed to know this as they cover more than the first 5 shown on home page. Copy & paste to new browser window.

http://store.allcomputerresources.com/index.html

Just looked your ecm up on the site looks like it almost 50% off now, way (by abt. $100) cheaper then we paid.

May should do a compression test on those cylinders to be sure its not head gasket.