Since Congress can only be held accountable every 2 or 6 years in elections, increase the level of accountability and introduce a system so that members of Congress and the Congress as a whole can be measured periodically (e.g. quarterly or annually) and their pay will be reduced or eliminated if certain levels of approval are not met.
A member of Congress will be paid the lesser of the individual or Congressional approval ratings. Should the Congress person be subject to the group rate, he/she would have incentive to work with Congress to improve ratings. And any failure for Congress to not deliver on anything that is mandated by the Constitution results in no pay.
Example pay grades:
0 - 20% = 0% of pay
20 - 30% = 20%
30 - 40% = 40%
40 - 50% = 60%
60 - 70% = 80%
70%+ = 100%