have you tried to perform a exhaust back pressure test? using a exhaust back pressure sensor PID you can tell whether it has a bad/plugged Cat or not, check air filter first.I have had a handful of times in the past 2 years that when I come to a stoplight that the engine shakes pretty good. But my main problem that just started is that when driving 5-15 minutes I cant seem to get above 1700-2000 rpm without having the engine bog down, let take my foot off the gas pedal and slowly add gas and it seems to come back, but this a every time occurance now. The truck always starts up great hot or cold, never stalls, or backfires. I am not getting any error codes, no smoke, FICM checks out good, changed oil and filter, changed both fuel filters, cleaned and replaced o rings on egr valve.
I would like some ideas, I was thinking injectors but I don't have the normal symptoms, could the engine be starving for fuel?