97 code help

hi all got a 97 with 75k, 3.5l
engine light kicked on today and i get 12 43 55.
whenm its cold it runs perfect but when it warms up it runs and drives but at idle the car wiggles around like crazy, tach dont move up and down that much, a little at times but nothing huge.
i get code 12, i've read that will pop up and dont worry about it, but the 43 stumps me. any help in a direction to go will be greatly appriciated, especially since im broke

also gas milage has sucked for awhile now, sometimes 300 plus a tank then next time 220. the idle has been allittle rough for a while, but now pretty bad and a light

12 is a prob with battery connection - but it also used to be a "I'm about to read out codes" code - so don't worry about it.

55 is an end code - if you get nothing after that, you're done reading codes.

43 is "peak primary cicuit current not achieved with the maximum dwell time" - which has to do with your coil - maybe. You'll need to check the coil primary and secondaries with a volt/ohm meter (cheap), as is the Haynes manual (a good start, but not complete) which contains this info.

Take off the air cleaner snorkel on the passenger side and look under it to find the ends of all the plug wires. Mark them and their terminals either by cylinder or position, and gently pull them off. The coil pack connector is right above them.

with the engine off, connect the pos + probe of the ohmeter to the B+ pin in the coil pack, and the neg - probe to each cylinder contact one at a time. The resistance of each should be between .45 and .65 ohms. If you get a flashing 000, a wildy ranging reading, or a consistently high or low reading, even after repeated attempts, the coil pack is probably bad.

Also check across the secondaries - they're in pairs, adjacent to each other - they should read 7000 to 15800 ohms. Any big discrepancies here would also be a reason to replace the coil pack.

Hope this helps. Mine is a '96, but I think they're the same.Keep in mind though, that a code for one thing may have many causes.

thanks for the info, it'll get me started figuring out whats wrong with her.

ok had ignition coil tested, tested ok, but still got new one to try cuz of them being known to test ok cold but be bad when they get hot. but still does same thing. dissconnected battery for awhile and now light is staying off. went for a 20 min drive and still no light, and i cant get it to read any codes. what else should i look to next,. oil looks fine and antifrezze in overflow looks nice n green and normal not low or anything, (i have my fingers crossed for not haveing a cracked intake gasket) even put fresh gas in, no diff.
HELP!

You might also check the plug wires and the plugs. A mildy fouled plug might cause it, or a leaky wire. Each wire should be less than 25K ohms. Look for any cracks or loose boots or connectors too.

Mine has a tiny wiggle @ idle, but not annoying if I run 89 octane or higher - 89 is recommended for 3.5L anyway. If nothing else, try filling up a nearly empty tank with premium and dump in some injector cleaner at the same time.

couple of other things

1 - try shooting some carb cleaner into the throttle bodies while working them...

2 - You'll need to look at the Haynes manual for this, but it's beyond explanation online - you might want to check synchronization of the throttle bodies too - not hard to do, just hard to explain w/ out pics

easy intake gasket diagnosis - remove the "3.5L" cover (4 #30 Torx) and spray carb cleaner at each juncture of the plenum and the manifold - take your time and do it from both the inside and outside of each inlet - any leak will cause the engine to stumble - you can also do it with smoke, watching for where the smoke gets sucked into

checked wires all were ok. just replaced plugs and wires about 4 months ago. didnt look at plugs yet, its 15 degrees out froze just doing the wires.drove it today, work and back 60 miles on highway and its runs fine when driving, still has power and all. and no engine light. wont show codes either just 12 then 55.
try to get out tommorrow after work and mess with it more supposed to be a whopping 28 degrees.
thanks for the help