Just changed plugs and went for a cruise tonight. The car felt sluggish at some points through mid RPM, no codes were thrown. Then at times it felt like it should. At WOT it felt fine.

1. Will a miss throw a trouble code? Is this a miss?

2. A bad FPR? Fuel pump?

3. At idle the RPMs would drop a tick or two and dash lights would dim very slightly.

4. Search function ain't working.

Experts enlighten me please.

 

OBDII cars will throw a multiple missfire code via flashing SES light.
If your car had a dead cylinder the engine would vibrate at idle. Dunno why it would feel sluggish and then normal at WOT. Any backfiring?

 

No backfiring.

So I would definately get a SES flash with any kind of miss? What about the rpm drop at idle?

 

You can, but not necessarily. Depends on what's causing the idle to drop. Did you unplug the battery to do the plugs? If so the unstable idle could be your PCM relearning. Still unsure what would cause the hesitation or missing at part throttle. Just check the easy **** first... make sure all your plug wires are securely fastened to the plugs and opti...

 

Well I should get a new AC Delco FPR in the mail this week. Hope that will cure the hard starts. I am beginning to think the 102k original fuel pump is the problem. Could the rpm drops and low rpm stumble be a fuel pump pondering a dump? I think I will order a Racetronix this week, going to need one eventually.

 

Usually if it's a fuel issue you'd have problems at WOT as well. Cheapest way to check that is buy yourself a fuel pressure gauge, put it on the car, drive around and see if it dips at all when the car is acting up.