1997 Chevy S-10 misfire

[quote:84fca5d959="KirkE"]Computer problem
1997 Chevy S-10 4 cyl Two Wheel Drive Manual 85000 miles
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Has miss-fire code P300.....With Modus, watch cylinder 1 and 4 miss during open loop, as soon as pcm goes in closed loop cyl 2 and 3 are misfiring, the truck does not mis while driving not a steady mis eather replaced both coils, icm, plugs and wires, can and crankl sensor fuel pressure within specs, f p regulator working properly also , vehicle also has 2 new injectors, cyl 2 and 3,..Will donate very well when a reply is made that will help us..Thank you, Kirk 480-586-4043[/quote:84fca5d959]
do a compression test
are you loosing coolant ?
test and or replace the ignition module