Modern vehicles like the Colorado have lots of sensors to help prevent major engine melt-downs. One of those is the sensor that tells the car the engine oil level is too low for safe operation. If that sensor is sending bad information to the car's computer, the vehicle might be programmed to go into limp-home mode or even shut down altogether to preserve the engine.

But the oil problem the car is reporting could also be dangerously low oil pressure or oil that has become too hot. The farther and faster you travel, the hotter the oil becomes (up to a point) and the thinner it becomes, meaning it may not be thick enough to sustain safe oil pressure. This could also be caused by a dud sensor, but it could also be a real situation. And like the low oil level sensor, this can force the engine into shutting itself down as a self-preservation measure.

Even if the two cars were from the same production month and year, you’ve got some serious mis-matches there; enough to make the job far more time, effort and money than it’s worth. For a start, the two-wheel-drive Colorado won’t have the extra differential and drive-shafts to mate with the twin drive-shafts that the all-wheel-drive gearbox will have. So you’d have to somehow blank that front driveshaft off. Or, add the front differential and axle which will also probably require different front suspension. Prop-shaft lengths are likely to be different between a manual and an automatic version of the same car, too.

Then there’s all the other things that can suddenly catch you out. In many cases, the manual and automatic versions of a particular car will have different transmission tunnels and different holes in the floor for the shifter to poke through. Even the centre consoles can be non-interchangeable. The dashboard of an automatic car with its PRNDL display will also be different to the manual one. Then there’s the question of wiring looms which can also be vastly different to suit the specific requirements of each driveline layout (a modern automatic needs lots of electrical inputs). In fact, the on-board computer is very likely to be different between the two transmissions on that basis as well.

Following on from that, what about the sensors to control the all-wheel-drive system? Or even the rotary dial inside the car to select the different four-wheel-drive modes? A two-wheel-drive car just won’t have them nor even possibly the access points to add them. And what about the real basics? Things like the automatic car not having a clutch pedal. That requires a full pedal change inside the car. None of this stuff is simple, easy or cheap.

To be honest, the engines themselves are very possibly interchangeable, but even if that’s all you swapped (and not the transmission) you’d still need to change the flywheel and plenty of little details.

By far the best advice is to simply buy the version of the Colorado you want.

Your problem could well be torque converter-related, but it could also be something else inside the transmission. The fact that the transmission will not shift back out of sixth gear even going uphill, suggests that there’s – in theory least – a problem with the electronics or hydraulics that control the shifting patterns. That the transmission is also shuddering is either a symptom caused by the same problem, or a result of a second fault in the unit.

It always raises suspicions when a problem crops up just after a vehicle has been serviced, and sometimes that suspicion is well placed. Have you double-checked the level of fluid in the transmission since it was flushed and refilled? Incorrect fluid levels can cause the sorts of problems you’re seeing. So can the incorrect grade of type of fluid used. You should check both these things first and move on from there if they check out okay.