Help with 1996 Silverado rough running intermittent starting.

I currently have no code. However I took data on my scanner twice. The
truck sputtered and ran a little rough as soon as I left the driveway.
It seem though the further I went it started to get better. Truck has
had a catylist system efficiency below threshold for a number of
months. I assumed it was a catalytic converter and would not be
related. Truck has 342,000 miles. New plugs, wires, cap and rotor in
April. Today I replaced Ignition control module and ignition coil.
Ensured continuity with battery ground on the ICM harness. Ensured
continuity on the white wire from computer to ICM.



Problem started as what felt like "slipping" several weeks ago when
leaving for work. Did not seem to be getting as many miles pertank
either.) Never had that problem again for the rest of the day. This
lasted for a few weeks. I put two bottles of fuel injection cleaner in
tank and filled up tank. A few days later went out to start and took
forever to start. Once did ran rough. Got the code P1351. Did above
diagostics. Getting 6 colts to the ICM harness. (calls for 1-4 in
book). Checked crank sensor. It is supposed to output "approximately"
5 volts but is outputting 4. Cleaned with a wire brush chasis ground.
Code has  not come back yet but I have not driven truck other than to
do the data test a few minutes ago. (And still seem to be exhibiting
problems).



On a whim I checked fuel pressure. It was within specs at 64 psi.
(Calls for 60-65). However, when turning the key off the pressure
drops down a great deal. In 5 minutes it dropped 30 psi. I think my
Haynes manual says this is abnormal but not sure.



is the truck safe to drive to work? It seems to get better as it warms
up but I dont want to get stranded. It is my daily driver and I dont
know what to do.



Here is the data I downloaded:





Location #1 (Test
1)



DTC-cnt                                0



Fuel Sys 1            OL



Fuel Sys 2            OL



Load_PCT(%)     4.7



ETC (F)                  108



Shrt Ft1 (%)        -3.1



LongFt1(%)         0.0



Shrt FT2 (%)        -3.9



LongFT2 (%)       0.0



MAP (in HG)       11.5



RPM (/min)        668



VSS (MPH)          0



Spark ADVC        -19



IAT (F)                   70



MAF (1b/min)   1.198



TP (%)                   0.0



02sB1S12=97B2S12=97



O2B1S2 (v)                          0.230



SHRTFTB1S1 (%)               -3.9



O2B1S2 (v)                          0.340



O2B2S1 (V)                         0.130



SHRT FT B2S1 (%)             -5.5



O2B2S2 (v)                          0.070



OBD                                       OBD2



Location #2 (Test
2)



DTC-cnt                                0



Fuel Sys 1            CL



Fuel Sys 2            CL



Load_PCT(%)     17.6



ETC (F)                  205



Shrt Ft1 (%)        1.6



LongFt1(%)         0.0



Shrt FT2 (%)        1.6



LongFT2 (%)       0.0



MAP (in HG)       26.6



RPM (/min)        1505



VSS (MPH)          41



Spark ADVC        -15



IAT (F)                   70



MAF (1b/min)   8.279



TP (%)                   42.4



02sB1S12=97B2S12=97



O2B1S2 (v)                          0.100



SHRTFTB1S1 (%)               3.9



O2B1S2 (v)                          0.670



O2B2S1 (V)                         0.110



SHRT FT B2S1 (%)             3.1



O2B2S2 (v)                          0.800



OBD                                       OBD2