Is it possible to manually adjust the idle w/ fuel injection

Yes it is possible. However it is (almost) never a good idea. Generally the throttle plate adjusting screw is sealed. It is sealed because if the idle is high it is usually a vaccum leak and adjusting the screw will only mask the problem, and can cause more damage by causing a lean condition.

Unless you had a backfire that bent the throttle plate, I would not touch the adjusting screw. The throttle body may be clogged up from the EGR or the IAC may not be working properly.

Then I would check the timing first. It may also be the throttle body plate is clogged up from EGR soot or the IAC passage is clogged.