GM-GMC: How do I set EDI ignition timing, vacuum leak, haynes manual

Question
Howdy,  I replaced the intake manifold on a 96 GMC Jimmy.  I marked the distributor and rotor before I removed it.  When I went to reinstall it the distributor did not seat all the was down into the oil pump.  Doubting my marks, I turned the distributor so it would seat.  She would not start.  Checked for spark at the coil and it was good.  Checked at the plugs, no spark.  Replaced the cap and rotor and I now have spark to the wires.  Set #1 Cylinder to TDC and placed the rotor between the cap contacts for cylinder 1 and 6 as per the Haynes manual.  She then had spark at #1.  She started, but has serious misfires.  Check engine light came on so I checked it with a code reader.  It shows code for intermittent miss.  Replaced plugs and wires.  Still shows code for intermittent miss, and is real rough, serious misfires.  Any suggestions??  Should I have set #1 Cylinder to TDC and placed the rotor on the cap contact for cylinder 1???



Thanks in advance,

Ray


Answer
A couple of possibilities here:

1) Make sure that you have the wires connected to the spark plugs in the correct firing order and rotation for the distributor.

2) Check for a major vacuum leak from a hose that was not reconnected.

3) Check for a vacuum leak where the intake and head surfaces meet.  I had a gasket slip on me once and cause this problem.