Tstat/Lean condition/limp mode question

[SykoraA4]

So i have been battling limp mode and a code for running lean for quite a while now, replaced the maf, and am still having problems. I will clear the code, and for like 100 miles it wont come back, but then ill look and see im only boosting 5psi. then the next time i accelerate ill get full boost back. but then ill go back into limp and the cel will come on. also on top of that, my thermostat is bad, and both my coolant and oil temp gauges barely move. (i know i shouldnt boost untill the coolant gauge is straight up but because of the tstat, i do drive for a bit to warm up, i dont know how bad it might be...)

so heres the crazy theory:
i hear my SAI pump when i start the car for a few minutes, and i will also hear it kick on for just a few seconds maybe 5 minutes of driving. could it be possible that because the thermostat is bad, its making the car think its cold, triggering the SAI pump to lean things out, and thus causing my intermittent limp mode? or am i just nuts...

[NorCal1.8T]

what is your lean code?

[SykoraA4]

p1128 if i remember correctly. i left my vag cable back at school or id double check.

[NorCal1.8T]

ok i dont know if you remember but i just had the same code. Replace your coolant sensor first of all, very very cheap(its the green one for the 1.8t). Now when i had the problem, i replaced the coolant sensor, then found out the BANK1(front) 02 sensor was bad so i bought a new one($160), i replaced a couple of bad vacuum hoses, and then i bought a brand new MAF($140) which ended up being bad out of the factory(my luck) so i exchanged it for another one, cleared the code and that solved my problem. Most of the time its the MAF. Start with all your vacuum hoses after you replace the coolant sensor. Check the ones that are in front of the engine also, they are kinda tucked in. Make sure you dont have ANY leaks. If that does not solve the problem, i would do a maf reading make sure the new one is good also. Then we can go from there.

[SykoraA4]

i should have mentioned that, i replaced the coolant sensor and the primary o2 sensor back in september. Ill double check the vacuum lines though. any chance you remember where you found your bad lines?
ps. happy thanksgiving!

[NorCal1.8T]

large and small l-hoses by the coolant reservoir, and one in front of the engine where the timing belt is. You could do a vacuum leak test, there is a diy for this but i cant find it right now. How many miles on the car?

[SykoraA4]

yeah, i have a fog machine back at school i was going to try and rig up when i do a pressure test, i just havent figured out how i want to go about doing that... the car has just over 120,000

[SykoraA4]

bump cause i still got nothin...