Find a locally owned muffler shop. Not a chain/franchise shop. They can weld it back together. The chain shops will insist on replacing the pipes

A crank but won't fire is caused by lack of fuel or improper fuel mixture, or no spark. Did this just start or have you had starting issues in the past? Is this no start caused right after fuel fillup? If so, try depressing the gas pedal while you crank the engine. If that works, get the purge valve checked out. Any other details you can provide will help.

On older GM vehicles with Distributorless waste-spark ignition systems, one ignition coil serves two cylinders. So when one coil pack fails, two cylinders won't fire. The fact that you don't get a drop in RPM when disconnecting 2 and 4, would indicate a bad coil pack servicing those cylinders. However, we don't know the year and engine in your vehicle, so I'm just guessing that you have a DIS ignition system.

The general answer is that it could be a bad door actuator or a bad ground connection for that actuator. A bad switch would affect all the door actuators. Usually, door actuators either work or they don't; they're usually not intermittent. So, I would start by cleaning the ground connection to that actuator to eliminate the possibility of a bad ground. Next, I'd check for corrosion inside the electrical connector to the actuator.

The instrument cluster in your vehicle gets its power from the Cluster/Theft Fuse 10A located in the Body Control Module located under the center console. That power comes into the cluster on a red/white wire terminal 14 of the connector at the cluster. The cluster ground is supplied on a black/white wire at terminal 6. The ground wire terminates at ground point G201 under the center console. So check the fuse first. Then check for power at terminal 14 and check for good ground at terminal 6 at the cluster connector. The cluster operates by digital data supplied by the body control module on terminals 7 & 8

This system uses two fuses, a circuit breaker and a relay to route power to the door switches. All three have to be operational in order for the windows to work. Check fuse #26 in the cabin in the left kick panel, Fuse SBF 4 in the engine compartment, circuit breaker on the left side of the dash, and the power window relay on the left side of the dash.

Checking the fuse/circuit breaker is the first step. If that's good, check for power coming into the master switch on the driver's door. If you don't see power, check for a broken wire in the door hinge area.

Removing the cylinder heads on boxer engines while the engine is still in the car is possible but not practical. To get the best result, remove the engine from the engine bay and mount it on an engine stand. Then remove the cylinder heads and old gaskets. Clean the surfaces properly and then mount new gaskets, following the steps listed in a shop manual. Torquing the head bolts in the correct order and to the correct torque is critical. Then mount the engine back in the engine bay. It's a big job and not well suited for a DIYer who's never done this before

When the ABS warning light comes on that means that the abs control module has detected a fault somewhere in the ABS system and has set a trouble code . So you'll need to get the trouble codes read. Once you have the code post it here and we can help you diagn

Remove the exhaust manifold. Remove the gasket. Clean the cylinder head surfaces and the manifold surfaces. Install new gasket. Reinstall manifold and torque to spec