I have a 91 Sedan DX ED3 with stock D15B2 DPFI 237,000 miles, and I have removed the stock air intake running a large cone style air filter directly off of the dpfi black PGM-FI housing. I have removed the restrictor plate AND the tandem valve from the throttle body keeping just the bowl style screen inside the housing... The engine has new O2 sensor, PCV, cleaned MAP & IACV, thoroughly cleaned injectors and right after I removed the tandem valve I properly reset the computer so it could relearn the idle mixture settings, AF mix, etc. I've noticed great performance gains, both at low rpms & WOT high rpms and the sound is throaty & mean too ...

Here's my question: Will allowing more air into the engine cause it to run lean enough to burn a valve??? or damage anything else internal?

I run 10-40 castrol gtx high mileage with purolator pure one premium filter and have changed @ 2500miles like clockwork. My oil looks almost new after 1500 miles of hard driving and it doesnt use any....

 

Nothing the computer can't compensate for. You didn't do anything that actually "allows" more air into the engine. All you did was unrestrict the path of the air on its way to the engine.