Getting a random misfire... On startup it sometimes revs high, then idle goes down and it lopes (stock GM cam), then stalls unless I give it some gas. When driving along at speed, it'll miss ocasionally and even more under load. When this happens (and when it lopes), RPMs/volts will drop in sync. Volts are fine when running normally before this happens.
I have changed:
MAF (bad - replaced with new which helped and stopped the error codes - also tested the new one by unplugging)
Fuel filter (was good - keeping the old as a spare)
Plugs + wires (I can get pictures if anybody wants of the removed parts)
Air filter is K&N drop-in and has been recharged recently
Two coils have been replaced and the control module have been replaced twice recently!
Camshaft position sensor has been recently replaced with proper matching part
I am thinking it's either the fuel injectors or the TPS. I'm open to other ideas. If you think it's fuel injectors or the throttle position sensor (?), how can I check or have it checked? I have been trying to fix this for weeks now and it's driving me crazy
The MAF screen may be SLIGHTLY bent (no fault of my own - have pics if requested) but it is clean and air flows through. The MAF sensor on the V6's are removable units housed inside the throttlebody before the valve. Not sure if the bent screen would cause this. It was running fine for a LONG time with the bent screen.
Car is a '99 with 115k miles on it. It has an electronic throttlebody (drive by wire).
It's a 3.8L V6 f-body but I figure maintenance is maintenance and an F-body is an F-body. I've asked in the V6 forums but haven't gotten much feedback.
P.S. NO CODES HAVE BEEN THROWN