97 suburban 5.7L vortec misfire

I've got a 97 suburban w/5.7L vortec w/120,000 miles. Recently it's developed a misfire. OBD-II scan returns only one code indictating misfire detected on #1 cylinder (P0301) No other generic or enhanced
pending/hard codes identified. I've replaced the cap,rotor, wires and plugs (gapped @60). This misfire is present at all rpm ranges but obviously most noticeable at idle or when first engaging transmission. The odd thing is that randomly it will dissappear under accelleration as if someone flipped a switch and will run clean for awhile. I erase the code and all is fine during the vehicle operation in which the misfire clears up, but usually the next morning problem resumes. Any help or furher diagnosis steps is greatly appreciated.
Thanks MB
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Sounds like a coolant seep into the intake. Any abnormal (compared to the others) deposition on the #1 plug?
VLJ
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This misfire is present at all rpm ranges but

I've removed the plugs numerous times and all are about identical in color/deposits. Compression tests all show about 100 on all cylinders. Forgot to mention this is a TBI fuel system. MB
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This misfire is present at all rpm ranges but

the
Read my reply over on the 2WD chevy group. It's MPFI, and 100psi is WAY low. 150-175 psi is normal for your engine.
Doc
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