Will 1998 saturn engine part fit an 1995 saturn engine

No, timing is not like that any more. Timing lights are almost obsolite. Your computer takes care of all of that now. Disconnect your battery for a few minutes and connect it again, this will reset your engine timing

I doubt it. Too much generational difference. Remember in 1996, the federally mandated OBD-II compliance standards went into effect-the new emissions requirements with On Board Diagnostics 2. (Before that, emissions and computerized controls were called OBD-I).
Don't give up yet, though. Very possible the engine block and heads are interchangeable. Check with a salvager's interchange manual about that. If you are good on that, you could swap the other engine parts from the old engine (like, possibly the intake manifold) onto the '98 engine. Or, if you are just asking if some parts from the '98 engine will fit the '95, then, again, check an interchange manual.

yes.

If you are replacing a DOHC 1998 engine with another DOHC 1998 engine yes it will work. Saturn only made two engines from 91-99 and they all had the same block, difference some were SOHC and others were DOHC. The number "1" after SL or SC or SW means SOHC while the number "2" after SC or SL or SW means a DOHC.

Note if one is an auto and the other manual you are going to have to swap the flywheel/ring gear stuff over.

There was a problem with 95-99 Saturn junction blocks. Loose fitting to pin connections in the actual connectors pulling loose which would create a similar symptom. Both under the instrument panel and in the engine compartment. You might be able to get a copy of the TSB from the Saturn dealer it is Bulletin No 03-08-45-001 issued May, 2003 Good luck.

No, you need a 96 through 98 engine, make sure the one you get is the same as yours, that is if you have an SL1 your donor car must be an SL1, SW1 or SC1 and if you have an SL2 then your donor car must be an SL2, an SW2, or an SC2. You can buy rebuilt engines for about 2000 with core exchange
might make more sense if you intend to keep it a while and if a manual then do the clutch while it is out.

same part should fit 96-99, call around to local junkyards. there are also some scavengers selling old saturn parts on ebay, contact one through an ad and put in a special order. usually a few old saturns being sold for parts on craigslist.

the SL seats were pretty interchangeable, so i would imagine the SC seats are as well. there are only 4 bolts so it does not take long to check/

It's a 4 cylinder, engine size 1.9L SOHC.
Napa oil filter number 21348.

the fuel pump is located inside the gas tank. You have to lower the gas tank, unlock the ring that holds it in, unhook the wires and fuel lines, and then you can lift it out.