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Is there a check engine light on?
When the problem is and isn't present compare spark from the wires. Using the engine as a ground check for spark to jump from the end of the wire to the ground. Compare to when the problem is present and not present. See if there is a noticabl difference in spark.
If spark is weak, you could have a bad coil. Also what kind of plugs did you use?
NExt, do you have access to a fuel pressure gauge? If possible check the fuel pressure and verify fuel pressure holds. 30-45psi is specification. Verify the fuel pressure isn't high or does not bleed off. This is important. If fuel pressure is too high, replace the fuel pressure reuglator for letting too much gas go to the injectors. This can cause a hard start. Also, if fuel pressure does not hold pressure, the regulator could be bad. You can also remove the return line from the fuel pressure regulator and smell for raw fuel.
If ok, let's move on to the PCM and some possible sensor issues.
First, unplug the mass air flow sensor and see if the problem goes away. The mass air flow sensor is the one located on the hose coming from the air filter box.
If no change, plug back it.
Next the coolant
temp sensor, the coolant temp sensor and Mass air flow sensors both can affect how much fuel the pcm thinks the vehicle needs, so both can cause a rich condition.
(Ohms) Temp F Temp C
31700 42900 68 20
13650 18650 104 40
6500 8900 140 60
3240 4440 176 80
1770 2370 212 100
980 1380 248 115