Why wont my car wont accelerate?

I have a 2004 toyota camry i just
bought it from a friend like 3 weeks
ago it was working perfectly fine. On
saturday my brother did the
oil,filters,and spark plugs change on
it. We went around to test it out and
it was working good,no check engine
light no nothing. We went to
take used oil to autozone , when i
turned it on to go home the check
engine light came on and it would
not accelerate until you hold the gas
down to a certain point. I took it on
the freeway and it felt like if it was
forcing and the rpm usually is at 3
but it was going up to 4 - 5. Also the
spark plugs that it had before the
gap was 7 and we google and called
autozone to make sure and it had to
be on 4.4 so thats how we put it.