Engine Missing

I'm working on figuring out this stupid miss situation I'm having. Sometimes it will run fine, but there is an obvious miss in the passenger side head. It seems the passenger side is afterfiring into the exhaust making a loud pop sound. When I run the codes I get system lean, so it must be dumping more fuel in. I don't even know where to go on this. I thought maybe tps (new one), or idle set wrong, but nothing seems to help, so I was thinking maybe one of the injectors is going bad. Anyone got any ideas? Car has 130,000 and original injectors too.

Oh and when it bucks like it's missing its like it is when the gas tank is really low and the engine studders if you go around a corner too sharp.

Also it does this from start up too. I was thinking maybe I need a fpr to fix the problem with a little more tuning capacity.

all the plugs look fine, just replaced and checked them and they all have sooty grey material on them, so lean. The codes confirm it with the 41 and 91. But even on start up the fuel pump kicks on fine and everything, but it takes a while to crank over and start. Been that way since I bought it, that's why I think maybe it is a fuel pressure problem...

timing set @10 btdc too, just checked

well thanks for that. I did an cylinder balance test and all turn out fine also. Could a bad ground be a problem? Or any other suggestions? Man I'm sick of troubleshooting.