ive searched and found some stuff i just swapped in a rebuilt 305 tbi into my 92 camaro and it wants to stall when stopping so i checked the engine codes and it pops up code 15 which is my coolant sensor which the plug broke on and just kind of sits there now and code 42,53,and 54 last month with old engine didnt have any of these so what could it be now?could one thing cause all of these codes or am i looking for a whole bunch of specific things for each code.my only real issue is when i start i smell gas? and when i stop it idles down to about 5 or 600 and wants to stall which is rather anoying just fixed timing and still does it i have it set to 2 degrees advanced