'98 Ram 5.9 misses at idle

From : ken

Q: 98 ram 5.9l misses when it idles and will set codes p302 and p305misfires. truck runs fine out on highway and tows travel trailer fine. i have changed plugs plug wires and distributor cap and rotor. i have also swapped fuel injectors from cyl 2 to 4 and cyl 5 to 7. error code stays the same and miss is the same. has anyone run into a similar problem or have any good ideas what the problem might be thanks .