MrPete

I recently bought a 85 190e 150k on it. The car had been sitting for about a 1 1/2 yrs. The inital problem with the car was the two pre-cats were completely clogged. Once that was fixed the car ran fine. I changed the cold start valve today, the car was hard to start. The car drove great. When I went out to start the car again, it started but then dropped to less than 1000 rpm and was hard to keep running. It also was backfireing in the throttle bowl (not sure the tech name). It seems to be getting to much fuel or out of time. Whats crazy is it was just running fine 15 min earlier. I went back and replaced the start valve to the original one, but the results were the same. Could this be a vacume line I may have pulled off. Here is what I have already done to the car.
New Plugs, cap & rotor, timed, replaced the fuel distribution (the boot on the bottom was really cracked), fuel filter, Pre-Cats, replaced the injectors.
Could this be a relay or fuse?? Also the fuel in the car is pretty old and I noticed it is now less that 1/4 tank. Any thoughts as to what the problem could be???