P0300 Code: Random or Multiple Cylinder Misfire Detected

I need a little help. I am 77 years old. I retired after 45 years as a heavy equip mechanic and service manager for the local Caterpillar dealer. I'm a pretty good mechanic but to old to be pulling wrenches anymore so I use a local repair shop with an excellent mechanic. I have a 2008 tundra 5.7 double cab with 169000 miles. Three weeks ago I started it from inside with the remote and let it warm up [20 degree day] for ten minutes. Drove about half a mile, heard a pop and it quit. Check engine light, 4w lo, vsc, lit up. Tried to restart, it would fire but not stay running. Checked the codes and got a P300, P306 & P308. Had it towed to my mechanic. He found on bad and one weak coil. Plugs and coils were original so I had all of them replaced. Since he had the top of the engine opened up two years ago at 157000 miles to replace secondary air pumps and valves he rechecked all wires and connections and grounds. It was due for annual NYS inspection so he told me to drive it for 60 to 75 miles to reset the emission sensors and then he could do the inspection. I drove it for a couple of days [88] miles. On third day I started it up from inside with the remote [another 20 degree day]. When I came out it was running rough. Checked and had P300 and P301 to P308. Cleared the codes, restarted and it ran fine. Took it back to my mechanic. He had it in the shop for two days and could find nothing wrong. Told me to drive to reset emission sensors. Put 118 miles on it this time with several stops and restarts. Took it back the same day, got the inspection done and went home. Truck sat for two days. I started it up sitting in the seat because I wanted to watch the gauges. It started and ran fine. Oil pressure went up about 3/4 of the gauge as usual with cold oil and then came back to its normal half way mark. The tach on cold start goes to about 1500. As the engine started to build temp the tach was dropping back to idle speed. When it hit 900 the engine started to run rough. Checked and had P301 to P308 codes again. Cleared the codes and the truck runs fine, throttle response is very strong and transmission shifts OK. I believe something on cold start is causing the problem. I don't mind clearing the code every day but I would appreciate any help or suggestions to clear the problem. I don't want to just throw new parts at it.

 

How does the MAF look? Try giving it a cleaning and check maf wiring connection.

 

I would check for vacuum leaks and fuel/air ratios possibly fuel injectors

 

Have you replaced your spark plugs?? I would have the mechanic check your spark plugs. If you're replaced them from the local auto store would be your best bet and stay away from Amazon and Ebay as some of their stuff is counterfeited.

I had a similar issue not too long ago, and cylinder 5 spark plug had some build up or reaction on the tip of the spark plug from there it started to trip up all the other plugs as well. Most people recommend to stay with Denso, and I would agree. I did autolite sparks and they failed at 70 or 80k miles. I went back with NGK sparks.

 

I had p0307 come up first. Cleared and drove it like I normally do, next day it came back. I could tell the idle was off just a little. Then I drove it to work and as I slowed down for a car turning, truck went limp with vcs and tractio light on and flashing CEL. Went out today and solder one of my wires back onto my ACIS valve. Starter the truck, went out on the highway, dogged the snot out of it. Used cruise control on the hwy, exited the hwy, went down a 40 mph road, start and stop just fine, slow take offs just fine. I could tell a difference in the torque and power with the ACIS working properly. So took her on the hwy again, mild acceleration, cruis control at 70 mph. Come back to go home, went to slow down for a turn and bam, flashing CEL, vsc, traction, God awful fumes from the exhaust, I'm going to guess raw fuel. Had a p0300, p0305 and the p0307. I got this truck in 2015, I have never changed the plugs or inspected the coils. But just started one day with no issues prior. So now I need to pull coils and plugs and investigate

 

Most of thevtime it is just a plug change that is needed. Maybe a coil but plugs first.

 

Changed all plugs over to denso long life iridium and started the truck, have white or grayish smoke out of the left tail pipe, flashing cel came back with p0300, p0301, p0305 and p0307. Kept clearing the codes until primarily p0307 was the only code. No codes for passenger side cylinders at all. I don't believe I have a coolant issue, don't believe I have a bad fuel pump or fuel pressure issue, the truck runs with poor idle, doesn't stall or die and starts right up. So jm going to clean the maf sensor and throttle body and see what that does, I can get a set of fuel injectors from parts geek for 110 bucks, mine are green and green is what these are.

 

These were the autolite spark plugs I took out, truck has approximately 276k on it. They are carboned up and smell like oil/fuel.

 

I would also look into changing out the PCV valve