Hello, I have an 86 firebird with a 2.8 that has developed a really rough idle and hard cold starting. I am wondering if anyone has some sort of troubleshooting guide because I'm really sick of guessing and spending money on parts, especially when there's so many possible explanations. I have taken it to a good mechanic and he replaced the fuel pump, which he said brought the pressure up to 44 from 30. Didn't help with the idle or the starting but did result in more horsepower. He said the idle was most likely the maf sensor but he couldn't get one for two weeks so I replaced it myself, no luck. Here is a list of all the things I've replaced on the car since I bought it a couple of months ago

Fuel pump relay, O2 sensor Fuel injectors (excluding the cold start injector), Fuel filter, Sparkplugs, plug wires, Fuel pump and strainer, Maf sensor.

The problem seems to be getting worse over time and today I could hardly keep it running even at higher rpms. I'm not looking to throw more money at it before I know for sure what the problem is. Any advice appreciated, thanks.

 

I should add there are no check engine lights

 

I have an 88’ factory service manual I just took a quick look and a few photos of the V6 trouble shooting pages, hope this helps.

 

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