Hello,
This may get long, but I will try to give some history on this. I can really use some help with this problem.

Got my 87 Firebird, 305 4bbl with stock CCQ-Jet. No mods, but I do have a K&N on it. 119K miles on it. It was running good until last weekend where it was cutting off on me during WOT. I thought it was odd, so I started with replacing the fuel filter. It was in ok shape, but I changed it since I had no idea how old it was.

Well, after doing that, it would not start. Fuel pump went out. So, got a new fuel pump and put it on. Started right up, ran real good during a short test.

So, today I got to drive the car for the first time after all the above was completed. It was running real good, smooth accelleration, nice smooth idle. All of this was expected as it was a good smooth runner before.

Then the SES light came on. But it was still running smooth.
Got to my destination. Upon leaving, SES light was off. Ok, it was a fluke, so I thought. Then it came on again. No problem. It was still running well.

But as I turned into my drive, something wierd happened. It started to idle rough. Around 500RPM or so, and it was varying around 150 RPM or so. Odd, needless to say.

Checked the codes... 15 - Coolant Temp Sensor.
Found the sensor plug broke. Fixed it. Idle still off. Would hover between 450 and 600 RPM but almost want to die. It still accellerates well and the like. Just idles like crap. And it smells like its a little rich now.

So, for the time being, I increased the idle speed screw just as a make-fix solution. I only increased it enough so I know it wont die.

This sounds like a vacuum issue to me, so I checked everything and everything seems to be in place with no cracks and the like. I dont think its the new fuel pump because I get no fuel starvation at WOT. But I am willing to entertain ideas.

One other thing, and I dont know if this will help or not. I dont know if any of you ever experienced this, but before these problems, you know if you take the air cleaner cover off, it may start running a little rough? Put it back on and it smooths out. Well, what it sounds like is like when I used to take the cover off.

I would be grateful for any ideas on how to get this thing idling smooth again.

Sorry for the long post... thought some history would help jog some ideas.

Thanks in advance.

 

One other thing... I did not replace the coolant sensor. I was just able to reattach the wires. But I am not sure if that was the right thing to do either. It looks like all the sensor is made of is another temp thermocouple of sorts. Could this be a source of issues as well?

Thanks again!!!!!!!!

 

Update... this AM took it out and the drivabilitiy problems did not occur until after about 20 min of driving.

Also replaced the CTS and the plug.

Im thinking is more of a vacuum issue.

Any ideas? Please?

Thanks.