Please Help!!

[Bentas1ent]

Hello All; My C-4 has been running great until today. It sat in my garage for 5 days. Upon trying to start it today it fought a little to start, then started and ran rough. When I tried to drive off it backfired and died. It then started right up again but every time I tried to step on the throttle it would backfire then take off. Then the check engine soon light came on. The idle is also now very rough, surging up and down. I brought it back and checked the code and it was a code 44 for lean exhaust. I cleared the code and tried again but the same results (backfire and code 44). Could someone suggest where I should start to look for the problem. Thank You, Steve.

 

[G Winter]

Could be EGR stuck open due to a piece of carbon. Dirty fuel filter is possible but usually don't come on that quickly.
Fuel pressure regulator is a bypass system,, could be stuck open but again unusual.
Throttle position sensor is also a possibility.