Hi
I recently had a "family friend" do a tuneup on my car (asked him for 150k service, he did a whole tuneup), and he used aftermarket parts (I found out after my check engine light came on and I took to the REAL repair shop, and they attributed it to the aftermarket parts--no serious problems detected, smoke test ok, etc).
My question is, how dangerous is it for me to ride around on these parts and is there anything I can do in my driving to avoid problems until I can afford to get replacement parts. I dont typically drive until weekends, daily I only take the kids to and from school (about 5 miles roundtrip). Weekends, though I drive long distances, maybe 75 mi RT on Sat and 50 RT on sunday.
I understand I can get catalyc converter issues or oxygen sensor can burn out etc, but perhaps you guys have some tips for how to avoid until I can get right parts in there.

PS Getting money back from "family friend" is not an option as he's jerked the whole family and everyone's mad at him, so now he's hiding out.