I am having the same problem in a way, passed everything except the HC (ppm) at Cruise which was 880 and the limit is 400. At Idle I get 331 and the limit is 400. When I had it at about 2500 RPM and holding during the test, the car would kinda, "pa-------pa-----pa-pa" out the exhaust. The truck has been running great giving me about 20mpg but I have also had some codes come on and off every once in a while in the past, 21, 25, & 26. So maybe the O2 sensor is going out but I am not an emission guy.

One thing I do know is I do not have a cat (got punched out about 6 years ago and I have never had a problem passing emissions).

So what do you think I should do? I know how to do everything to my car so that is not a problem, I just don't want to buy a cat and O2 sensor and still not pass, so are their some other things I should do?

In WA I can go to a professional and spend $150 and the state will give me a waiver so I can still get tags. I just don't know a mechanic that wouldn't bend me over backwards...

 

I was failing for high HC. Put a new cat in and went from 660 to 29...
You may not have had issues before but I bet a new/functional cat would help

 

Alright thanks man, I appreciate it, I think that is what needs to be done

 

So today I take my new '87 4R in for the emissions so that I can get it registered. Unfortunately I failed for both HC and CO. At high speed RPM I had 516 for HC (Limit 200) and 6.62 on CO (1.20 limit). At low speed I was 976 for HC (200 limit) and 6.01 for CO (1.20 limit). Didn't have time to do anything so I went to work. I am going to follow the suggestions above like cleaning the throttle body, adjusting my idle down to 800 (at around 1000 now), adjusting my timing, checking my plug wires, and checking my TPS. As my emissions issues are different than the OP's I was wondering if anyone had any other suggestions for things to check out before I get my 4R retested. Thanks in advance.

Ian