P0171: 35 times: becoming more frequent.

Question

Changed m a f, intake gasket, plug wires. Also checked for vacuum leak @ pcv, intake manifold, etc. none found.

Answer 1

P0171 Fuel trim lean Bank 1

The best way to check this condition is with a KOER (Key on engine running) test, any other code such as a IMRC being stuck open will cause a lean code condition. Another cause is coolant seepage, any coolant loss occuring