Hey people, We've got a 2006 Grand Caravan with a couple of issues that I can't seem to pin point. I'm not sure if they're connected so I've listed them below. Any help is HIGHLY appreciated!

1) The heater does work in the van but only if we're on the expressway going fast. We can start the van up and drive it around town but the heat won't blow. Once we hit the highway, the blower kicks on and everything is nice. The coolant is at the recommended level and I don't see any leaks. Would one of the relays cause an issue like this?

2) the brake lights are melting into their sockets. Once the turning signal (or brake light) goes out, we can remove the bulb and part of the plastic is melted. This has happened twice over the past year - so it's not often at all.

3) The van has a hard time accelerating so we take it easy and ease the pedal down when we drive. The van is idling at 0 and when we hit the gas (in park), it rev's up but stops around 2100 with a hard stutter. I thought maybe the catalytic converter is clogged but the exhaust pipe is kicking with hot air! Someone tried to steal the converter and had half of the pipe cut off but we got a new pipe welded onto it, sealing it off. I attached a video of the revving.

Thanks in advance!