SOLVED: '73 2.0 w/ FI started burping/backfiring, (sounds like popcorn in the microwave) Options

[DC_neun_vierzehn]

My '73 2.0 w/ fuel injection started backfiring a couple of days ago and seems to have gotten progressively worse in the last couple of days. It's not constant. Seems to worsen as engine warms up. I've owned the car since April and it ran fine when I purchased it.

Where should I start with trouble shooting?

Disclaimer - my mechanic/engine skills are very limited.

Thanks in advance.

[DC_neun_vierzehn]

To close the loop on this one in case anyone searches for these symptoms and wants to know what it could be ...

My mechanic detected exhaust leak (loose exhaust manifold studs and one of them was actually missing). The missing stud had stripped threads in the head, but the other loose studs just needed new studs and washers to seal. The stud that had stripped head thread was able to be at least temporarily sealed ... for how long we'll find out. He said they will need to drop in an insert to properly fix, but I may just wait to permanently address if/when I do a motor rebuild.

So for now ... the exhaust leaks were addressed and the random/occasional backfiring has been fixed. She's running strong again!

Thanks all for the input.