  The cosmic acceleration problem remains one of the most significant
challenges in cosmology. One of the proposed solutions to this problem is the
modification of gravity on large scales. In this paper, we explore the
well-known $\mu$-$\Sigma$ parametrization scenarios and confront them with
observational data, including the cosmic microwave background (CMB) radiation
from the Wilkinson Microwave Anisotropy Probe (WMAP), Atacama Cosmology
Telescope (ACT), and South Pole Telescope (SPT), as well as large-scale
structure data from the Sloan Digital Sky Survey (SDSS: BAO+RSD) and Pantheon
Supernovae (SN) catalog. We employ a Bayesian framework to constrain the model
parameters and discuss the implications of our results on the viability of
modified gravity theories. Our analysis reveals the strengths and limitations
of the $\mu$-$\Sigma$ parametrization and provides valuable insights into the
nature of gravity on cosmological scales. From the joint analysis of the ACT +
WMAP + SDSS + SN, we find $\mu_0 -1 = 0.02 \pm 0.19$ and $\Sigma_0 -1 = 0.021
\pm 0.068$ at 68% CL. In light of the SPT + WMAP + SDSS + SN, we find $\mu_0 -1
= 0.07 \pm 0.18$ and $\Sigma_0 -1 = -0.009^{+0.078}_{-0.11}$ at 68% CL. In all
the analyses carried out, we do not find any deviations from the theory of
general relativity. Our results represent an observational update on the
well-known $\mu$-$\Sigma$ parameterization in view of current CMB data,
independent and competitive with the constraints obtained with the Planck data.
