Engine slows down when going up hills

Good afternoon.

Two possibilities:

1. Low fuel pressure. If you have low pressure from a weak pump, it will cause this. You can test the pressure with a gauge. If you do not have one you can rent one at a parts store.

2. Clogged catalytic converter. This is more of a common failure. If the exhaust becomes clogged, it cannot breathe and will cause reduced power under load. There is back pressure gauge that you can test the back pressure. You would remove an O2 sensor and insert the gauge and test the reading you can also test by unbolting the exhaust pipes at the exhaust manifolds and take it for a ride.

Roy