P0303 misfire code on 97 Silverado truck with 5.7 vortex engine

Check engine code question:

Using my diagnostic scanner, I found I have a code P0303 (cylinder #3 misfire) on my truck. Initially, I have tried changing plugs and plug wires with same results. The compression reading is the same for all cylinders. I suspect the injectors might be the culprit but the job involved is too much which requires removing the intake manifold. Any other test I can do before I do this?

Check engine code answer:

You never mentioned if the distributor cap was replaced on this but this problem is very common on this model. Just make sure that you use AC Delco parts not the aftermarket parts. With regards to your injectors, try checking the internal engine vacuum reading first by plugging the vacuum openings (pcv and vent hole) on both valve covers. Install a vacuum gage in the oil dipstick tube and see if you get any vacuum when engine is on idle. If it does, your intake gasket is leaking.

If intake gasket is OK, the injectors can be removed and checked for spray pattern and compared to each other. This is done by removing the upper intake and lifting the injectors. For more details, please contact ATS so I can send you the wiring diagram.