Lisa's car started shuddering as if it was running on three cylinders. We got it home and I borrowed John's OBD2 ( or OBDII) data reader, and got back a P0301 error, misfile on Cylinder 1.
At Pep Boys to buy plugs and wires, I learned that the Echo does not have wires, but instead an ignition coil module for each spark plug!
Replaced the plugs, none of them seemed worse than the others, but they all showed great wear and were well more than double the prescribed gap.
That didn't fix it. Googled for a while to double check which cylinder was #1, and came across the duh idea to swap two ignition modules around and see if the problem follows the module. It did, so I went back to Pep Boys (despite reading warnings that aftermarket modules may not work due to not adhering to Toyota specs) and got the one module that they had in stock, and now the Echo is happy again. Also did some research into the viability for replacing the injectors or cleaning them, and even bought some cleaner but haven't used it yet.
My favorite links found:
A story about using the OBD2 reader: http://www.toyotanation.com/forum/132-9th-generation-2003-2008/369315-fixed-my-p0171-code-thanks-forum.html
A story about a guy with a Ford who got a P0301 error, but he had the bad brake booster problem that I had with the Pinto: http://www.rangerpowersports.com/forum/f10/p0174-p0302-p0301-vacuum-leak-254083.html
Some idiotic answers from ranndom people on the Internet about P0301: http://wiki.answers.com/Q/What_is_code_P0300_Random_Misfire_Detected_P0302_and_P0303_on_a_Toyota_Corolla_and_how_do_you_repair_it
A guy whose similar Echo cut out. I don't think that he got and answer here: http://www.toyotalexusforum.com/toyota-camry-club/5887-toyota-echo-2000-misfire.html
A case of a bad coil: http://www.toyotanation.com/forum/26-yaris-vitz-echo-forum/370063-testing-ignition-coils-2001-echo.html
The cylinder order: http://wiki.answers.com/Q/What_is_the_firing_order_for_a_Toyota_Echo_1.5_V4
The long story where a guy got replacement coils off the Internet and they turned out to be junk: http://www.justanswer.com/toyota/1je9q-2001-toyota-echo-cylinder-check-engine-light-on-cyl-misfire.html
Replacing the Fuel Injectors: I lost the history leading up to this drawing, but the page that I was on insisted that you had to remove the valve cover first. Looking at the engine, it doesn't seem as though that would be required, but here's te diagram: http://s3.amazonaws.com/2cp-images/question_images/9553/large.jpg?1309087734
This ehow seems to agree with me: http://www.ehow.com/how_7868615_replace-fuel-injectors-1zz-fe.html
