Definitely hit it with a timing light, improper timing can lead to what you describe and engine damage if you let it go on too long. Look at the top of the AFM, if the silicone seal is cut it's probably been jacked with at which point you should look for a junkyard replacement if setting the timing correctly doesn't fix the problem.

'87 4-Runner--DD/wheeler, 4.3 swap coming soon
'89 Supra--E85 powered 2jz NA-T Swap, 533rwhp 497ft-lbs
'89 Festiva, turboed BP swap powered by megasquirt