No Start issues- now limp mode magically appeared

[vibeguycanada]

Starting to get very frustrated with my 07 Vibe 1.8 5 speed manual. Already replaced the starter twice in the last 4 years but did it with used parts being cheap and the last one i got looked "new".
Then my car started just not starting- symptoms similar to a bad battery, but battery tested good a few weeks ago when i got oil changed, above the rated cranking amps. So i assumed stater was still good and started my troubleshooting with the Clutch starter bypass switch- used paperclip to close circuit- nothing- then next i took out the starter relay fuse- jumped that with paperclip one day and starter worked- but the starter was running till i took paperclip out- got new relay fuse- still no start- put old one back in and i can feel it click- so back to drawing board- must be the starter solenoid- or bad connection somewhere.

Next pulled the battery terminal cables off and did the old baking soda and water solution. Keep in mind before car would start now and then going from 50% of tries down to 2%...so i been bump starting it by pushing it and get to speed pop clutch and it drivers fine. Ordered new starter with solenoid. Then i got to bump start it and car is all the sudden in limp mode for some reason(no idea why, maybe i got water or bakign soda on a sensor- no idea- maybe just a weird coincidence. Also checked started fuse under hood it was fine.
I can barely bump start it and it wont rev past 1700 rpm so cant really drive it anywhere over 10 km/hr. and it seems like if i tried to go up a hill it would stall and die. Check engine light has been on for years- never affected drivability and it turns on and off randomly.

Now i have two problems- no start (new starter coming today and i can install myself). Left negative battery terminal off overnight as the 25 mins i disconnected it last night didnt change anything.....

So i am wondering if i bumped a wire somewhere or got water or baking soda on a sensor (don't see this being likely) or is my pcm on its way out and finally died??? Would a bad starter/solenoid cause these issues?

Where do i look next ? My buddy has the obd2 code reader he said he can bring it by to see if that tells us anything....last time starter went it triggered a code for crankshaft sensor- and when i put new starter it the light turned off so i don't know if i can always trust the reader.

The only thing after the starter i could see it being is a break in the wire somewhere to the starter , or possibly the PCM/ ECU module . If I got a PCM out of another vibe (like form a scrapyard) with the exact same pcm part # is it plug and play or do i need it programmed? No anti-theft on vehicle .Same with buying a remanufactured one online? they say they are plug and play but i cant see why one out of the same vehicle wouldn't work....???

I am at my wits end as every time i think i have the issue solved turns out i don't. Shops in my area just wanna sell expensive parts and i don;t know if i can trust them so trying to figure this out on my own....this forum has been the most help so far. I am at the point now of almost wanting to give up and tow the car and buy a new one but would hate to do that if its something simple as i have just replaced a bunch of things and if this was fixed the vehicle should be reliable. Help!