Put key in ignition, turn all the way forward, but not trying to start. Let alarm cycle 2 times, when it stops the 2nd time, remove key and alarm should be disarmed. This will only work if it is a factory alarm.
try using a quality fuel injector cleaner as the problem may be bad injector operation
if the engine was washed at the inspection , could be water in harness connection or shorting out electronic components
have the fault codes read to check for problem sensors before you panic and waste money
P0141 o2 sensor heater circuit malfunction bank 1 sensor 2
po455 evaporative emission control system leak Gross leak
po303 misfire cylinder three
p0732 gear two incorrect ratio
p0734 gear 4 incorrect ratio
HMA/HAC shows a span of 1996-2001 Transmissions, there are a few different options to choose from, Depending on motor size, and year, The picture enclosed shows all manual transmissions. Hopefully this helps you.