99 GCM Vortec Service Engine Soon light

[mod49k]

My 99 GMC will start flashing the service engine soon light when I'm pulling a load up a hill (usually in 2nd gear) at high rpm's. It has done this one other time and the code at that time said it was multiple misfires. I have changed the fuel filter, plugs, wires and rotor. I have not seemed to have a problem for about 1500 miles but now the SES light came on in the same scenario. I'm going to have the code read tomorrow. Could this be due to problems in my injectors?

Any ideas?

[GM-Tech]

It could be an injector. A flashing SES light indicates a misfire is occuring that could potentially damage the catalytic converter.