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Recently my car started misfiring on start-up and idling very rough. It threw several codes: P300, P301, P304, P1128, P1130.

I noticed a small coolant leak at the same time. I took it to the shop.

They diagnosed the leak as the water pump and replaced it. At the same time, they replaced the serpentine belt. They said it was fixed, so I picked it up.

It wasn't.

It was still idling rough and misfiring, but no longer throwing the codes for it.

After a bit of online research, I determined the misfiring in cylinders 1 and 4 was most likely caused by old, cracked ignition coils getting some coolant on them from the leak, since those are the two front cylinders.

Yesterday I installed 6 new ignition coils and 6 new spark plugs. When I did, I found some oil in the spark plug tubes of cylinders 1 and 4, and a little in cylinder 2 as well. This situation is one I had not known about, and was afraid was something terrible, but then discovered those tubes are removable and it's a common thing. I have ordered six new tubes/seals.

First question is, would that leaking immediately cause the roughness and misfiring?

The only codes I got after I installed the new coils and plugs were the 1128 and 1130. Interestingly, when those codes were displayed, the idle was pretty smooth. When I cleared those codes, while the car was running, the idle immediately went to s.h.i.t. (Next time they appear, I won't clear them.)

Any help is appreciated.

Now, on to the Durametric.

I took a few pages from the service manual, started the car, and recorded all the numbers I could get. Here's what's going on. (I know the Cats are bad. That's nothing new, but I've been running fine on them, except for an occasional CEL, for 3-4 years.)

Numbers that are out of range are in bold.

Idle Speed (expect 740 +/-40) --- in range
Load Signal [Engine Load?] (expect 1.0 ms +/-0.25) --- 17-18%
Mass Air Flow (expect 15 +/-1.25) --- 11-12
Engine Temp (expect 90 +/-5 C) --- 76.5C
Ignition Timing (expect 5.3 +/-0.5 deg crk) --- 2.2 ms
Oil Temp (expect 90.0 +/-5 C) --- 67.5 C
Oxygen Sensing, All cylinders (expect 1.0 +/- 0.05) -- all in range
Adaptation Range 2, Bank 1 FRA (expect 0.96 +/- 0.03) --- 1.06
Adaptation Range 2, Bank 2 FRA --- 1.05
Adaptation Range 1, Bank 1 RKAT? (expect 0.00 +/- 0.06) --- 3.00
Adaptation Range 1, Bank 2 RKAT? --- 3.09
O2 sensor voltage
---Ahead of Cat (expect 0.07 - 0.79 --- Both fluctuating between .09 to .82
---Behind Cat (expect 0.64 - 0.79 --- Both fluctuating between .09 to .75
O2 sensor resistance
---Ahead of Cat --- Both banks steady at 64
---Behind Cat --- Bank 1 steady at 64, Bank 2 steady at 128 (This one is bold because it's the odd man out.)
Camshaft Position 1 Deviation (expect 0.0 +/- 4) --- -9.22 (steady regardless of RPM)
Camshaft Position 2 Deviation --- -8.66 (steady regardless of RPM)
Rough Running (expect 0.0 +/- 1.5) -- 7.6/8.8 (jumps back and forth abruptly)
Misfire Detection --- 0 for all cylinders

I also removed the oil filler cap with it idling and there's clear suction and MAF numbers drop, and the idle immediately goes to s.h.i.t.. There is also suction when removing the dipstick, but the idle is only slightly affected.

Any help I can get before I take it in for some (probably) expensive work would be appreciated.