2002 Silverado 5.3 96k

Last week my tank got to about the 1/4-1/8 mark and my truck start to idle rough. I normally dont allow it to get that low so I'm not sure how long I've had this problem. I let it run low again today to see if I had the problem. I do, Almost as if it wants to die. I fill the tank and idles fine. Today I added a bottle of sea foam to my tank. Any Ideas on my problem?

 

fuel injector or plugs and wires, but ud think if it was the plugs and wires it would be constant not just low on gas?

 

Well I am due for a tune up, so that will be my next step.

 

The fuel pump is not submerged (just the pick-up) when the tank is under 1/4 so you could be getting the pump hotter than normal and the pressure may be dropping. Do a pressure check when it is full and then when it is idling rough and compare the 2 numbers. A tune up should have nothing to do with fuel level.

 

So I changed all the plugs and wires, noticed I had a cracked coil. Replaced that. Oil change, new filters.

No matter how much gas is in it now I'm still having a rough idle. Sorta like a vibration and a studder every 5 seconds or so.

I replaced the plugs with what the prev owner had in it, copper. Ive since found out that the correct plugs are iridium. Could this be the problem? either way should I pony up the money and buy new iridium plugs?