Never Ending Cel (P0302, P0304, P0110, P0120, P1133, P1153) With Many

[ToysNLexus]

Ok guys...yielding to the forum SOS! Which by the way, I've probably spent a day total reading around this site and it is an unbeatable resource and kudos to everyone for helping everyone.

Storytime, the girlfriend has a '99 RX300 that started to idle rough and lack power and spitting CEL's...so, having built 3 Toyota 4x4's from frame up, including 2 engine re-builds, I jump right in. Here's what's transpired and what's been done:

July 18th, 2013 - Codes pulled P0302, P0304, P0300 and P0120.

ACTION - changed all Ignition Coils and all spark plugs and tested resistance on all fuel injectors but #3 (bugger to get at as I didn't remove intake). Also cleaned MAF sensor and changed air filter. Codes cleared.

Car runs great for a day, lacks a bit of get up and go but no CEL.

July 20th...Codes P0120, P1133, P1153 pop up, car doesn't sputter but lacks power off the line. I order TPS (P0120 related). Try measuring TPS and continuity seems fine but I'm taking no chances with the Mrs. car. Codes cleared, ECU reset with fuse pull.

July 21st...TPS arrived, have not installed but additional codes popping up - P0110, P0100, P1154...cleared as I will be picking part up and replacing TPS shortly.

July 24th...TPS in hand finally but not installed yet and the damn P0306 comes up again with car sputtering and CEL flashing.

I will be testing both new and old TPS side by side this afternoon (bench test resistance), but I am in serious need of what else to look for if this doesn't solve my problems...I'm into this for some serious pocket change now and don't give up easily, plus my man card is on the line with the GF.

With how many problems and the diversity of them, I'm thinking:

- Ground wire problem?

- A/F Sensor problem?

- Plugged Cat? (What's the best way to check this anyways, rattle check?)

Any and all help hugely appreciated!

-Neal