trying to figure out a 91 244 5spd manual with lh3.1

I bought it for a project and will tow it home in the next week or so, just trying to plan my attack on it!

car starts and runs but rough idle/ shaking engine I heard it run for several minutes and po said it gets worse when the engine gets hotter.

I don't have any personal experience with lh3.1

I attempted to retrieve any codes but didn't expect to really find any because battery had been dead - had to be jumped to start and no cel light was on. I couldn't get anything from the red light at all on the test box though - seemed completely dead.

po threw a lot of tries at solving it - he had two white label 572 ecu's but said swapping didn't make any difference. crank position sensor is new. injectors are new. fp regulator is new. po says he also had the head rebuilt to try to solve it - with no improvement. I did notice that the throttle body on the car was the older style with a black adjustment knob so it must have been changed out. I'm wondering if it has the correct tps - how different is the lh3.1 tps - can you tell which it is by sight? could the correct lh3.1 tps have been mounted on a earlier throttle body or could a lh2.4 tps have been plugged into the car's harness- are the electrical connectors the same?

I didn't look too closely at the amm either - I know its a different type for lh3.1 - can they be identified by sight? are the electrical connectors different or could the wrong type have been plugged in?

Anyway, my backup plan if I can't solve it would be to convert it to lh2.4. Has anyone done this? Would I just need to replace the AMM, TPS ECU? would it be a plug and play swap or would I need to replace the engine wiring harness, or anything else?

Any other suggestions from someone with lh3.1 experience?

Thats a lot of questions- but I'd appreciate any help anyone can give!

Jim