is there a diffrenc betweewn those 2 years of engiens that makes then awhole lot beter?

 

The cam is different and MAF vs Speed Density

 

The runners are also different in the fact that they don't have the hole for the 9th (CS) injector in them anymore. The throttle bodies are also different. Also, MAF was from 85-89 and SD was from 90-92. The ECM change was a year after the runner/injector change.

 

ahhh cam was the same from 87-... and SD came in 90.

Cold start and spark plugs are different. I belive there was a colder plug put in the 88's. Dont belive me, ask for a 86-86 plug, and ask for a 88-89 plug... 87 has R43ts, 88 has R45ts.
None make them better, but as time went on SD and then dual cats improved performance.
here is the cam specs. Only thing changed was the cam specs for the 350/305 5spd cam.
1985 (L69 and LB9)
305 AT 14088843 .403 .415 202 206 114.5 (115/-114)

1986 (LB9)
305 AT 14094097 .350 .385 178 194 109.0 (106/-112)

1987
305 AT (LB9 10088155* .350 .384 179 194 109.0 (108/-112)
305 5spd / 350 AT
(LB9/ L98) 14093643* .404 .415 202 207 114.5 (115/-114)
305
(LM1 Police Pack.) 14093640* .383 .404 291 202 112 (108/-116)
1988, 1989
305 AT 10088155* .350 .384 179 194 109.0 (108/-112)
305 5spd / 350 AT 10066049* .415 .430 207 213 117.0 (116/-118)
1990-1992
305 5spd / 305 AT 10088155* .350 .384 179 194 109.0
305 G92 5spd / 350 AT 10111773* .413 .428 202 207 114.5 (116/-116)