Upon my return on a 300 mile trip, my 1994 z28 started acting foolish.

When pulling up to a redlight with the clutch disengaged, the rpms drop swiftly to 500, sometimes she simply dies. The strange issue also occurs while down-shifting too slow. The SEL will light up too for a few minutes.

In instances where the idle drops to 500, I can rev the engine smoothly, and the rpms still drop back. Only when I pull up to another stop will the rpms sometimes resume to the normal range.

She'll start right up and idle smooth in other instances where she dies. No misses, plenty of power as usual.

Something I found strange was that when the rpms dropped to around 500, she didn't sound as if she was struggling, rather a smooth low idle.

I'm thinking a sensor, any ideas?

Also, if this helps, most of my driving is highway, I run 10w-40, in result my engine has been running noticably cooler, right on the 1/4 mark.

Would the pcm think the engine is cold, thus supplying more fuel, choking her out?

 

best thing to do would be to scan for codes and see what that ses light is all about. check fuel pressure, check fuel filter, check a few plugs to see if there foulin, check the iac motor/valve, check air filter see if they need cleanin. if you have a maf check it to see if its dirty or looks damaged.