So I had a high idle problem. $550 dollars, a new fuel pressure regulator, filter, and brake master cylinder ( unrelated ) later I have trouble starting her cold. High idle is fixed though. My fuel economy restored. Went on highways today for several hours, hit 80 mph just fine then suddenly lost power. struggled to keep her at 50 mph. I floored the pedal and no response. I could feel that the power would come and go. No sputtering, or stalling which is good on a Houston hwy. I did fill the tank with regular unleaded $3.15 p/gl. before going on freeways (1h +/-). Any ideas?

 

Check all connections: AFM, CHTS, TPS, all plug wires.

Cold start troubles: Check air regulator and cold start injector.

Or take it back to the shop and tell them it's not fixed.