hard to pickup speed below 35 MPH

my 96 Oldsmobile Cutlass cierra 4 Cyclinder 2.2L

as of late has a tendency to have problems picking up speed, but when it does and it gets past 35 MPH, everything is fine.

it originally started doing that at first it had a vibration to it, cant say I noticed it since then but the problem occurs every now and then picking up speed.

Could this be a throttle sensor?

Could be a misfire, could be a lot of things, based on your description it is hard to tell, a scan should be done to look at sensor inputs and misfire counts.

Whats the possibility of it being the timing chain?

I am noticing this when the A/C is running it puts such a strain on the engine to where it seems to have low power, but it picks up a considerable amount when the AC is off.

Also to note, the engine itself and transmission has over 160k on it.

Any loss of engine power will be exaggerated with the ac on, especially in a 4 cyl. engine.

it wasnt exaggerated because an AC is not going to drag a cars power down to that point unless something is wrong somewhere.

Problem was diagnosed though as bad brake calipers, sure enough no more problems..........until recently it started doing it again.

Brake Power Booster possibly?

seems the master cylinder is pumping, but I dont know.

The post stated a loss of power is exaggerated with the ac on, right? Which is correct on any car especially a 4 cyl. So back you are again, do the brakes still drag. What does the m/c is pumping mean?

Have to turn AC off to gain speed, thats all I know, I cant say for sure anymore if its really losing power, ODB Scan showed the engine running fine with nothing wrong, good manifold pressure, good timing, everything else.

But turning the AC off to gain speed is hardly an issue after changing the calipers, I could turn if off and notice a boost in speed, dont know if thats normal or not, but the original problem I had is trying to come back it seems after about 2 weeks of changing calipers and all.

The M/C is pumping fluid as I have checked that out when I had back tire and all off to see what the shoes looked like. Although nothing is for certain.