Manually inserting if not done correctly (you don't just insert the code in one spot for it to work) will get you undesired results.
thanks for your help and advice. still searching on why this is happening. i've been using the module to track conversions for several months now and scrolling back, I do see orders being tracked, just not all of them and usually paypal orders.

to address your last point, do you mean to say I can't just paste the google conversion tracking code into my checkout success page and be done with it? what else would i be missing?