To preface; 2 weeks ago I purchased my first car which is an MY05 RBP with a 5MT. It has a lot of miles at 187k but had a full engine rebuild with a new turbo, clutch, flywheel, etc. at 169k which was all standard OEM parts from the SKU numbers I checked on the paperwork. I've been really enjoying the car so far and can't wait to get the terrible head unit replaced with the JDM unit.
Unfortunately, since this is my first car I'm bad with a manual and have killed it quite a few times, shifting improperly and bucking, etc. When coming off a stop I often over-rev on accident and jerk a bit, or I kill the car by not giving it enough gas.
So, I'm having two problems:
Recently as I've been getting better at not killing the car and bucking (still happens), I'm still finding it difficult shifting into first gear. It almost feels like it isn't slotting into place or engaging properly. I have no easy way to describe this as I'm really new to cars. I was thinking it might be the shifter bushings or synchros? Sometimes I noticed I can't even get it into first while my clutch pedal is shoved to the floor. Like today when pulling into my apartments, I tried to go into first from third after putting it in neutral after slowing down (between 5-10mph at most) for the turn in, and when I tried to put it into first, it just wouldn't slot into gear no matter what I did until I threw it into 2nd and buckled forward.
I sat in my coworkers 4th gen WRX and the shifter still had a loose feeling, but actually sliding into gears felt smooth and like it was slotting perfectly into place. He tried my car and said it felt basically the same to him, but I notice how much firmer the WRX felt especially sliding into first gear compared to mine.
My second problem is that occasionally - and in the last few days I've noticed it more - in first and recently second, as I press down the pedal, my revs climb fast, but my acceleration is much slower than usual. It also makes a very high pitched 'rrrrr' sound as if it's trying really hard but just not going that fast. Earlier today I was in first and it finally engaged properly and I felt a solid boost in first up to redline (first time ever revving that high) so I know what it should normally feel like, I just have no clue what could make it be fine sometimes and not fine others. I have no problems above second gear, with most of the time second gear giving tons of power. I typically drive to and from work (it's all short back roads) between first and third gear, as I never really go above 40mph. I do occasionally do small pulls along main roads but never really past 5.5k RPM or so.
I recently changed my oil using 5W-30 Rotella with the RX-8 Tokyo Roki oil filter through reading on here about a week ago and it went well. I checked all my oil levels for everything today and all was fine except needing some washer fluid which can be taken care of at another time. So I fear that I've burnt out the clutch already and hopefully not the flywheel too as I really can't afford to replace either right now having just purchased the car. Thing is, I don't smell a burning smell when driving which is what I gather I should be smelling if it's a bad clutch. But I have no clue what that actually smells like and my nose isn't the best so who knows.
As a side note, I've noticed that under the front dash I hear a gurgling sound. Could this be air in the coolant? The sound continues to happen for about 5 seconds after I turn off the car, but not always. It happened when I wasn't running the AC either, so I don't think it's the actuator motor that I read about on here.
Would greatly appreciate any suggestions on what might be the issues here. Thanks for the help.