i just got my tranny rebuilt, and so it seems to be shifting fine, but my stalling problem seems to have turned into something much worse.. my engine sound strange accelerating out of 1 and second (partial or wot) and i'm not sure what the sound is, but there are popping random popping sounds and thumping as if someone was hitting the bottom of my car with a bat or something... freeway, engine sound smooths down to normal, and no pops or thumps... can anyone describe briefly the differences between the 3 things in my subject and what they sound like so i can troubleshoot? thanks.

p.s. my ecu was giving me temp sensor voltage and batt voltage errors which i knew to be false, i switched out the ecu and it gave me only an iac error which i am going to try to switch out also... but are these likely to be the problem? plugs seemed clean when i pulled them out couple weeks ago.. but i will probably try changing those too

A bad coolant temp sensor will do exactly what you describe.

yeah thats one of the codes i was getting on my old ecu... that the ect sensor was out of voltage range... so changed it, cost me 40 bucks to find out that wasn't the problem, this was about 2-3 weeks ago... so unless something is causing it to go bad, i'm assuming its my ecu, but could the ecu ect error be causing such a dramatic problem? i'll give you the specific codes in order-
12 - pcm disconnected within last 50 cycle ons
44 - ect voltage error
22 - battery temp sensor voltage error
55 - end of code
also battery light was on

i forgot the number, but when i swapped the new one in, it only gave me one code for iac motor error

i also just switched to an optima battery, changed to gold plated terminal to be sure, tested on and off the battery voltage which reads 13-14volts, so i know power is good

ok, so i changed the sparkplugs to ngk vpowers gapped at .44 which i think should be good, there was heavy black deposit on cylinder 1, which may have been from when i used some intake cleaner from the mitsu technician, the change made my car run better, but still very lossy power on the low end, still getting the popping/thumping which seems to be loudest, or coming, from my intake, also my engine sound is actually strange both at low and high, sounds like maybe retarded timing? could my ecu be going into limp mode? do they do that?

my car is acting the same but i also get smoke coming out of my exhaust if i let it idle. anyone have any ideas?