I did the search and unless I missed something none of the posts dealt with my particular problem. My '85 is giving me fits on cold start. First of all, the car is heavily modded with the 165 ecm upgrade, 383 engine with a pretty hefty cam, Edelbrock Pro Flo intake and an LS style throttle body. I have a custom tune that has worked fine for over 4 years so I can't see that as a problem, I start it for the first time of the day, it barely turns over and it is running, it will idle fairly well considering the cam but if I drive away it will not run smooth if I am at a steady, slower speed. If I open it up it is gone immediately but I slow down and it is back to stumbling. Once I have driven it about 10 minutes it straightens out and runs perfect with no issues at all. I have a A/F ratio gauge and it is around 10-11 to 1 at idle once it straightens out is idles at 13-14 to 1. I have checked and rechecked everything and just put in a new heated O2 sensor. When it is acting up it seems it could be the maf but if it were that it would not get better. I have no cats, long tube headers and 3 inch into 2.5 exhaust with stainless magnaflow mufflers. I also have a fuel pressure gauge on the pillar and with vacuum off it is at 42 lbs. of pressure about 38 with vacuum on.
If anyone can give me an idea where to go next I sure would be grateful.
Oh, I forgot, no radical fuel pressure loss when shut down, just a gradual drop
Also, the tps is set at.542 and is smooth thru the range of travel.

 

Is this something that just started or has it been always rich? Any recent changes?

 

No recent changes and yes it just started this a couple weeks ago.

 

I pulled a couple spark plugs last night, they look perfect, no sign of rich condition.

 

Check the basics, are the wires and cap good?

 

All new or a couple months old Delco cap Taylor wires. BUT I got it taken care of. The heated O2 was only putting out .24 volts when it is supposed to be .5+, the fuse in the gauges position was blown, no power to the maf, and last, the tps had somehow moved and it was set at .57 instead of .54. I know it is said you can run the tps considerably higher but for some reason my car doesn't like more than .54 All issues are gone. Thanks to bjankuski and Willie (383vette) for your responses.

 

Glad you got it sorted out. Your car sure is sensitive to the tps setting.

 

It sure seems that way I think it is the LS style throttle body, the tps is normally not adjustable so I have to use the LS tps and then elongate the holes so it can be adjusted. If I raise the setting to .56 or more the engine will run great as long as I'm running it hard but if I try to cruise at a steady speed it stumbles and grumbles all the time. With it set at .54, acceleration is smooth and steady at all times.