A long stretch of road near East Heckington was to be reduced from 50mph to 40mph.
However, councillors were concerned that the size of the restriction was unnecessary and could lead to dangerous overtaking.
The updated 40mph zone plans are half the size of before at around 1,400 metres, and are more tightly focused around East Heckington.
When it previously came to the Planning and Regulation Committee in November, councillors said the plans needed a rethink.
Councillor Mary Austin said: “This is a major road in the East Midlands with a large amount of heavy traffic. I’m worried that once traffic leaves 40mph, all hell will break loose. Everyone is going to be jockeying to get past each other.
“With it being such a long, long stretch, there could be unforeseen consequences the moment vehicles are out.”
Speed surveys found that traffic averaged between 42 and 46 mph in the stretch.
There have been 15 accidents on that stretch of the A17 in the previous five years.
One resulted in a woman being killed when a car swerved into the opposite lane, and two more were listed as serious collisions.
Councillor Paula Ashleigh-Morris also voiced doubts at November’s committee meeting.
“I was surprised to find there were only 15 accidents resulting in injuries on this stretch in the last five years,” she said.
“We have very few good roads into Boston – this one cracks along.
“Where I live on a B road in Langrick, we’ve had considerably more accidents as HGVs head up to Immingham. This change needs a rethink.”
The revised plans will be discussed at a Lincolnshire County Council meeting on Monday, January 16.