What's wrong with my car

Have a 2004 Mercury Grand marquis with over
200000 miles on it. Solid car no problems ran great
excellent acceleration smooth pick up shifted
great. Idled fine AC worked great no problems.
Took in to get new tires and battery replaced due
to age and an alignment. Car well maintained. No
problems ran great. Exceptional.
Shop says can't do alignment need new front
struts. Ok roads out here pretty bad. No biggie.
Shop says need new drive line. Cautious but shop
is reputable. So ok replace. Took forever due to
parts sourcing problems.
Get car back and not right. Rough running idles
poorly hesitation at highway speeds.
Take back to mechanic said everything fine clears
code. Drive home no AC fuel gauge doesn't
move.fuel door ajar light now on . Shifting poorly.
Now before I went in for tires car ran like a champ
smooth fast good pickup idle smooth fuel gauge
worked AC worked.
I pulled codes got 0356. Plug fro harness to cop
was loose took care of that. Highway speed
hesitation disappeared.
No fuel gauge no AC though. Any thoughts before I
take it back. Check engine light comes on. As well
as fuel door ajar lamp on. Help. Any ideas would
be helpful.
Tired of getting runaround from shop