Missing on acceleration, trouble codes...
 

'97 Z28 5.7L V8

Friends car has been missing a bit upon acceleration. Hooked up the scan tool and found these:

P0174 System too lean, bank 2
P0171 System too lean, bank 1
P0300 Cylinder misfire detected
P0400 EGR flow malfunction
P0507 Idle control system, RPM higher than expected

Where do we start with this?

I'd get the egr system fixed first. Then, see how the car runs.

We'll do that. Thanks for the advice on where to start.

If you think about the 2 major problems you have with misfires and lean. Chances are good you are running lean which is causing the misfires. I suggest you have the injectors professionally cleaned either on the engine or off.

Incidentally tell him not to run the vehicle while it's burning lean as major damage will result.

So, is Seafoam through the gas tank enough to clean the injectors or should they be taken out and cleaned? How difficult is removal of the injectors?

I cleaned my injectors using an air compressor and the car's battery. Just use the 12V battery source to cause the injectors to pulse and pump air through them. I had a few little chunks of crap fly out of mine. If that doesn't help, have them professionally cleaned.

The best way is on the engine while it's running. The pro simply hooks a can of cleaner to the fuel rail and shuts off the fuel pump and disconnects the FPR. The engine simply runs on the can of cleaner until it runs out (about 10 minutes) and it's clean.

I like this method best because is also cleans the fuel rails. I bought the connection hoses and use 3m cleaner because they have a can that does not require a regulator.

Cleaners run through the fuel tank are ok for maintaining cleanliness however they are too weak to clear a clog like you are talking about in a short amount of time. By the time they did work, the engine would have already been damaged due to running too lean.

Is the 3M cleaner a "do it yourself" job? How much do the connection hoses cost? Do they connect to the schrader valve? Any other procedures to be aware of?

Yes it hooks to the valve. The hose by itself 6 years ago was $100.00 Leave it to the pros.