01 Toyota Solara Engine Light - suggestions please!

2001 Toyota Solara V6 with 60k miles. Engine light went on (continuous, not flashing). The only noticeable issue is definite engine roughness (miss fire ??) daily, when first started from cold, particularly under heavy load (hills). Engine runs without apparent issue after warm up. The local Toyota stealer (I wont name names, but Boise Idaho) hooked it up to reader, detected “mis fire on cyl 4” and wrote it up for ~“replace all three coils and timing belt”. $900. Now wait a durn minute, 3 coils ? Coils are not mysteriously linked. Belt at 60k? Hmm Toyota says 100k. We left $100 lighter but still unenlightened.

Later, sent it to a local guy who read out “mis fire on cyl 6” and backed off HIS suggestion to replace all 3 coils when asked “why all three ??”.

Hoping for the simple solution, I installed Toyota plugs and wires on it - Significantly, noted that all 3 FRONT plugs were identically caked with fairly heavy white / gray build up on (twin) electrodes and down the insulator, while center electrode erosion was not apparent, while all 3 BACK plugs were NOT coated with deposits, instead identically had very thin blackish / brown coloration, pretty normal looking, with perhaps some excessive center electrode erosion. Car seemed to run good, but “Check Engine” light came back on in a few days use and cold roughness re-occurred.

I next noted some thick grease on the particular coil that was originally installed on #4 , between the coil body and the lead connection to the rear cylinder. Engine is fairly clean and tight, so no apparent foreign source of grease / oil for the one coil, thus I assumed a possible cracked coil case, and replaced that one coil. “Check Engine” light came back on in a few days use. Symptoms similar.

This car had one significant issue in the past that was dealt with at the end of warranty. Wife’s car, with me doing over-the top oil change (every ~5k) schedule. I drove it ONE DANG DAY and it died with some indication of low oil ( I forget what the clue was). Turns out that the engine was probably running on one or two quarts by then! Apparently the upper intake manifold had sludged up, causing most of the crankcase oil to be sucked into the cylinders. Arghhh. Toyota put a “new improved” manifold on it, cleaned some of the sludge out (pulling the lower pan - I recall cylinder walls looking OK, such as I could see, and Toyota dealer indicated hat was as far as they were going). Believe that they admitted the sludge up was caused by the original manifold design. Lately started monitoring oil use to check for rings / walls damage.

Never did anything else, especially not O2 sensors, nor have ever disturbed the intake system. Squirted some carb cleaner around while running (hoping it would vanish in a fireball and puff of smoke = mooting the problem) but did not detect any intake air leaks at idle conditions.

So, obviously, one bank of cylinders is being affected different than the other bank ( front “bad” ?). Lost my faith and too much money relying on code readers, dealers and “experts”.

Willing to swap a few more parts before learning to enjoy the little orange engine picture that smiles at me where ever I go.

REQUEST- can anyone suggest a few things logical to cause ? Suggestions please ? Thanks !

Please condense it to, “Current symptoms with the Beast”. In the meantime, go to this link and compare your spark plugs with these pictures. Tell us what matches, and include condensation. http://www.gnttype.org/techarea/engine/plugs.html

I would add that the actural code (like "P1234") would also be helpful.  Often things get lost in the interpretation.

I have the same issue with a 2001 highlander. Didnt hear that it could be intake manifold. Will have to check that out. I did hear people say that it could be the valve seals. I wonder if it is the rings. In any case, it is due to the fact that the engine runs very hot and standard oil cant take the heat. The dealer recommends synthetic oil and I agree. I also read that using 50% auto trans fluid and 50% oil could help clean the sludge out. So far it does seem to help the smoke, but not the oil use. I am taking it to the dealer (i hate dealers) for them to check it out. They are not going to do the work. I will do it myself.