i have an 85 p/u with a 22re with 245,000 miles on it.runs great and strong.no mods except a downey header.it is failing on nox.i have had it in the shop and had it fully diagnosed and checked out.they cleaned out the egr system,put on new cat and muffler,and are clueless as to what the problem may be.anyone with similar problems please let me know what you think
