My dad has a 1995 chevrolet S10 blazer with a 4.3 cpi vortec engine. We changed the engine with one from a 1994 chevy S10 blazer with a good powerful engine. The 95 has a newer distributor with a crank positioning system so we had to change the timing chain cover. The ses light is on and it runs very slugish and burns a lot of gas, yet it idles very smoothly. we've pulled the distributor in and out plenty of times and cant seem to get it running better. My dad still thinks its out of time or just isnt advancing but even with instructions and pictures we've had no luck. With #1 cylinder at tdc where should the rotor point? We've changed the cpi and fuel filter. The inside of the intake looks a little to oily (maybe pcv valve) and the fuel pump screams when it gets hot. Thanx for the help.

 

Getting that SES code read would be a good place to start. At least it might give you something to go on.