bad CTS cause no 4th gear? Dirty MAF cause bad fuel mileage?

[bufmatmuslepants]

There was a discussion on LS1tech about the vortec 5.7s and people were saying they get 18-21 highway with their vortec 5.7 GMT400s, and I only see 14 in mine no matter if Im doing 65 or 80. Some guys said that it is very critical on these motors to keep the MAF clean and that fresh O2s could help. Mine did throw an SES light about 2000 miles ago and when my brother pulled the code it said O2 sensor I believe, but he cleared it and it hasnt come back.

I bought the truck cheap in late October (so only seen winter blend fuel, could be 1 issue) because the PO thought a poppet valve was stuck open causing the motor to flood and be hard to start, so he thought he needed a new spider injection. The other issue was that it wouldnt go into 4th gear, so he thought the trans was failing. No SES lights were on the dash. I bought it, drove it 5 miles to my grandparents, replaced the 1-2 shift solenoid knowing that could be the issue on a 4L60e not having 4th gear, threw 2 bottles of cheap lethal fuel injector cleaner in it at 1/2 tank so 4x more concentrated than recommended (http://shop.advanceautoparts.com/p/b...ner#fragment-1), and started heading home 300 miles but for the first 100 miles, still no 4th gear. After 100 miles I left a gas station and it went 1st, 2nd, 3rd, then it studdered HARD and I thought it was going to stall and finally threw the SES light, then smoothly shifted into 4th and ran 10x better. The next 200 miles it ran great, I pulled over a few times on the highway and did 0-80mph runs at WOT and it was perfect. When I got home I went to advance and read the codes and it said "coolant temp sensor high voltage", so I replaced the waterpump sensor and cleared the code and it ran perfect from then on.

Questions:
If the PCM reads between 0 and -40 degrees water temp, will it keep the trans out of 4th to try to warm up the coolant by running higher RPM? What is the PCM logic to try to warm up the engine, like fuel, idle, shift points, etc.

When the PCM throws an SES light for the CTS high voltage, does it start ignoring the CTS and go from a table instead, hence why it ran better with the SES light on?

The motor feels kinda sluggish when not at WOT, I know in LTx motors, at WOT it ignores the O2 sensors, could the time it threw the O2 sensor code be a hint that one is failing, causing the sluggish performance when not at WOT, and my poor fuel economy? Or is a dirty MAF more likely the culprit for bad fuel economy? What do you guys use to clean the MAF?

I dont know much about the service history on the truck, except I asked the guy the last time he had changed the trans fluid and he showed me a marker mark on the firewall where it said like 126k miles was the last time he did it, and it had 168 when I bought it.

I was poking around under the hood the other day and found 2 ignition coils, yes TWO. 1 was mounted properly but disconnected, and another was just sitting on the intake manifold and connected. I plugged in the one mounted properly and threw the other one in my center console, and it drove fine for the 1000 mile trip home from NY, but the next day it wouldnt start, so I put the other one back on and it fired back up. Does the ignition coil need a proper ground (bolted to the motor) to give a better reference, which could cause weak spark and bad fuel mileage? There was no difference in fuel economy with either coil, but the one mounted was going bad.