Hi all I'm new here and just wanted to say hello ive been reading these forums for quite awhile and finally decided to make an account because ive had this problem with my 420a that no one else has semmed to have. It all started when i had a high flow cat welded on my exhaust and the dipsh*t welder didnt ground somthing out right and ended up frying my ecu.. After replacing a bunch of emmisions parts and other things i thought cuda been the problem i had it diagnosed at a local shop, finnaly realizing he had fried my ecu i put another one in from an older model(mines a 99). My car finally was running again but only on 2 cylinders, so i took it back to the shop and they still said i had the wrong ecu after searching for hours on forums I realized the older models had different ecu wiring harnesses so i switched a few wires around and it runs great now except now it smokes out the exhaust and has a bad smell. If anyone could help me with this I would greatly appreciate it. Thank You

ps. sorry if i posted this in the wrong section