My sons' Stealth suddenly aquired a miss @idle, and surging bucking @ speed, 3 weeks ago. I told him to do a normal tune up.... plugs, wires... and even put new gaskets on the intake plenum (need to remove the intake to change plugs).No change.Took it to a Dodge dealer, and they ran the thing through their normal 'tests'. All they could find wrong is an actuator motor that changes the intake plenums' runner length...well, 6 hours shop time, a new motor actuator, and 9 bucks for a can of cumbustion chamber cleaner the bill came to ~$500... the 'miss @ idle' is gone, but it still misses pretty badly when ever the engine is not accelerating. Any gear, any speed. Whenever the engine is held at a constant rpm, it starts to buck and miss.Soon as I 'nail it', it screams to life, and it's business-as-usual.First thing that comes to my limited knowledge is: vehicle speed sensor? The reason I say this is because it acts sounds just like any computer controlled that is in Neutral,vehicle is stopped, and the engine is revved to 2500-3000 without a load (and it's missing, spitting and farting)...Soon as you put it in gear, and the computer 'sees' car is in motion, all is well!Does this sound like I'm on the right warpath here?(this is Mitsubishi built car, for dodge, and trying to 'learn' Japanese is not easy!)

I got one thatll make you scratch yer head....Been having the exact same problem on my little beater truck I drive to work. 93 Toyota pick up. Thing would sit there and idle ALL DAY LONG smooth as silk. Put it in gear and try to accelerate, it would fall on its face unless I really stood on it then it would come to life and bounce off the rev limiter all day long. Once I got it up above 3000 rpm, it was as if nothing was even wrong with it. Below that and it wouldnt even get out of its own way. Only one code stored and that was for O2 sensor. So I did the usual routine. Pulled plugs, looked good so regapped and put back in. Put new set of wires, cap and rotor on, no change. Even put a new coil on, ran the exact same way. The whole time Im thinkin about this code that has been stored for ages, and I figure what do I have to lose? So I disconect the plug at the O2 sensor. Thing runs like a scared chicken. I have no clue why that would have any bearing on the way it would run, but it does. Like I said, this wasnt a new code at all, its been on for a loooong time but I just havent cared enough to replace the sensor. So, whats the moral of this story? I dont have any idea other than Im probably going to scramble your brains even farther. Just when you think you have a vehicle figured out, itll throw a curveball at ya. Good luck!Have you tested your throttle position sensor? Rereading your post reminded me of a problrm I had on a car before and thats what it was. If youve got a manual you should be able to confirm resistance of the sensor...

finally!!after scouring the various forums, either Dodge or Mitsubishi, I found a common problem with the 91-92 models:Bad capacitors inside the ecm.So, this weekend, my son popped his out, and cracked it open. He didn't see anything at first... but I snagged my 3X power 'specs' and sure enough, there it was! one capacitor had puked a trail of brown snot... and it flowed across about 4 different circuits.... So, I think the problem has been discovered.Found a rebuilder in tenn. (ASI) and for $150 (free shipping both ways) and a lifetime warranty plus, they'll flash it with the latest version.... hopefully this is the 'final answer'.I was told about 5 day turn around.

Cool... At least you found it...

got email notification today that the ECM is FIXED, and is ON IT"S WAY HOME!!Pretty cool, that I got an email stating the part was received on Monday, another one on Tues stating the part was assigned to tech XYZ, and today's stating it was shipped out @ 8:15 am EST.Should have it in my hot hands on Monday or Tues... But it sounds like we are in for a butt load of snow.. which of course will make any 'test runs' dicey..update: ONE WEEK LATERgot it installed , and after it's initial 'learning' mode, it leaped to life. Smooth as a sewing machine.of course, the rebuild also has 'security seal' on the cover, so I can't peek at what they did! (unless I want to void the warranty)