A couple weird things going on.....

Ok let me start off with this. I own a 1991 Celica GT-S with the 2.2L 5SFE engine, automatic transmission. Now i have put a LOT of work into this thing and it feels never ending, but lately i had an exhaust leak at the flexpipe due to bad motor mounts, fixed the motor mounts but held off on the leak. the engine started missing occasionally. did a tune up (plugs, wires, dist. cap, and rotor) that didnt fix it. fix the exhaust leak, didnt fix it. took it to a buddy of mine who is a mech and he checked the timing, it was way advance up to about 22. he bumped it back and that smoothed everything out. its running GREAT and sounds awesome. now to my current problems, ever since he bumped back the timing the engine feels like it bogs down while driving, it feels like the transmission is slipping but im not 100% sure, check the tranny fluid and it was just a tad low, put some in it but it didnt help. now im not sure what to do, i REALLY dont want to rebuild the tranny and i DEFINITELY dont want to sell the car...... im just kinda depressed right now.........

One more bit of info.... ever since i changed the brakes the brake pedal vibrates with engine speed.....THIS IS JUST A GUESS but is there a chance that the "BOGGING" that i feel could be something with the brakes, like the brakes engaging slightly??.......but then again it all started when the timing was bumped back......... ugh............

one more thing...... is there a possibility that if i bump the timing to 15 (currently at 10) if that would help it........ ANY help would be GREATLY appreciated........ and sorry about writing you a book, i just wanted you all to know everything thats goin on..............

UGH!! thank you........:banghead: