no because if the gravity was affecting it, it would be increasing it. the effect would be much greater the closer it got to a large gravity source such as the sun. light that passed within a small distance of the sun would be effected a million times more than one that did not come anywhere near it.
all stars have a unique "fingerprint" of light spectrum. If gravity was effecting it that fingerprint would be red/blue shifted a lot when it passed near the sun when compaired to the same star when the earth was between the star and the sun. The effect of the sun on the light passing near it has been studied and no red/blue shifting has been found. If it had, the theory would have been changed.
This is not to say that there might not be a very small amount of effect, but not as much as you are saying. Also the effect of gravity of the sun on light approaching it would be in the opposite direction. the light that is coming from away from the sun would be accelerated, not slowed down. Light leaving a blackhole or something is red shifted because it is moving away. light that is coming to us from the stars would be coming towards a gravity sourse, so it would blue shifted.
