1989 tbi 360 runs rough cold

[ray hall]

Ok so my 89 360 is doing some strange things. I had a code 13 which I posted about a few weeks ago but nobody responded. I put a spare map sensor on it I had and the code stopped showing up but now when it's cold or its sat a little bit after it been ran and you start it up it will normal for a few seconds then starts backfiring off and on. Smells like it's running rich then it will start shuddering out and missing almost die then tev way up and smooth out then repeat. It will do this about 5 or 10 minutes then it will smooth out and run perfect until it cools down then it will do it again. Since that started after I changed the map sensor I figured I had 2 bad map sensors so bbn I just bought a new one and put it on still the same issue. I currently have no codes and I'm not sure where to go with this. Injectors look to be spraying fine. Has about a year old fuel pump. New egr valve last year. What gives? Once its warmed up its fine

 

[ray hall]

It also has a new o2 sensor about a month old. Changed it when I put the headers on it

 

[Kenny K]

Sorry I don't have a solution for you but I'm experiencing the same thing. I've replaced the IAC valve, MAP sensor and The TPS. Cleaned the throttle body. New PCV valve. No codes, hooked it up to a scanner and when the symptoms are happening it is running rich STFT confirms. I would also appreciate any help.