98 GC with miss in cyl 3 &4

[shuffler]

Have 98 GC with an I-6 with 98000. Engine has developed a miss in cyc 3 & 4. Plugs in cyl 3 &4 are not black but are not clean like in the other cyls. Have changed plugs, wires, cap, rotor. Moved the injectors in cyc 1 & 2 to cyl 3 & 4 and still misses on cyl 3 & 4. Fuel pressure okay. Used DVOM to measure resistance in inj all read the same OHM. Using DVOM appears inj are being pulsed okay by computer. Engine misses at idle and throughout RPM range. Haven't checked crankshaft or camshaft sensors as I would think if they were defective it would affect more than these 2 cyls. NO check engine light as of today. Problem started last night. Exhaust smells as if engine running rich.

Does anyone know what might be causing this engine to miss. Have read previous threads but found none fitting this problem
Thanks

[Cam7]

Usally if you have engine miss you have a code multiple missfire with 303 & 304. Since you have moved the Injectors around its not bad injectors. Try moving the plugs around to see if any change. Next thing in line is to do compresson ckeck to see if 3&4 are in line with the rest of the cylinders. Might pull the valve cover and see if the rockers are working right. Last it could be a bad pcm.

[shuffler]

Did a compression check and found that the head gasket was blown between cyls 3 & 4. Had head resurfaced and everything works great now.