OUCH - they screwed you HARD on that one. That's less than $5 in parts, including screw-down hose clamps to replace the crappy one-time ones from the factory. Those check valves are less than $1 each from usplastic.com, and as you said, it's 5 minute job.

1/4" PP Standard Check Valves | U.S. Plastic Corp.

 

Did you happen to fix your problem? I have the EXACT same problems with you and i have been trying to figure it out for a while, i feel like i have some loss of power too doesnt feel as punchy as it use to be at higher speeds. Any ideas?

 

no solution yet. next chance i get to work on it is tuesday. ill let you know!

 

well i got a new speed sensor in and no longer have the EPC/limp mode problem. but now the scanner tells me my MAF sensor is bad. got a new one and hopefully will change it out tomorrow.